Artificial joint components including mechanized synovial fluid deflecting structures

ABSTRACT

Prosthetic artificial joints are described, including hip, knee and shoulder joints. In some embodiments, a artificial joint prosthesis includes: a bone-facing surface of a artificial joint prosthesis, the bone-facing surface configured to face a bone-prosthesis interface in vivo; a non-contact surface of the artificial joint prosthesis, the non-contact surface adjacent to the bone-facing surface of the artificial joint prosthesis; at least one fluid deflection structure positioned adjacent to the non-contact surface, the fluid deflection structure positioned to deflect synovial fluid away from the bone-prosthesis interface in vivo; and a mechanism attached to the fluid deflection structure, the mechanism operable to move the fluid deflection structure to direct synovial fluid away from the bone-prosthesis interface in vivo.

CROSS-REFERENCE TO RELATED APPLICATIONS

If an Application Data Sheet (ADS) has been filed on the filing date ofthis application, it is incorporated by reference herein. Anyapplications claimed on the ADS for priority under 35 U.S.C. §§119, 120,121, or 365(c), and any and all parent, grandparent, great-grandparent,etc. applications of such applications, are also incorporated byreference, including any priority claims made in those applications andany material incorporated by reference, to the extent such subjectmatter is not inconsistent herewith.

The present application is related to and/or claims the benefit of theearliest available effective filing date(s) from the following listedapplication(s) (the “Priority Applications”), if any, listed below(e.g., claims earliest available priority dates for other thanprovisional patent applications or claims benefits under 35 USC §119(e)for provisional patent applications, for any and all parent,grandparent, great-grandparent, etc. applications of the PriorityApplication(s)). In addition, the present application is related to the“Related Applications,” if any, listed below.

PRIORITY APPLICATIONS

-   -   For purposes of the USPTO extra-statutory requirements, the        present application constitutes a continuation-in-part of U.S.        patent application Ser. No. 13/628,442, entitled ARTIFICIAL        JOINT COMPONENTS INCLUDING SYNOVIAL FLUID DEFLECTING STRUCTURES,        naming Edward S. Boyden; Gregory J. Della Rocca; Daniel Hawkins;        Roderick A. Hyde; Robert Langer; Eric C. Leuthardt; Terence        Myckatyn; Parag Jitendra Parikh; Dennis J. Rivet; Joshua S.        Shimony; Michael A. Smith; and Clarence T. Tegreene as        inventors, filed 27 Sep. 2012 with attorney docket no.        0411-002-008-000000, which is currently co-pending.    -   For purposes of the USPTO extra-statutory requirements, the        present application constitutes a continuation-in-part of U.S.        patent application Ser. No. 13/629,918, entitled ARTIFICIAL        JOINT COMPONENTS INCLUDING SYNOVIAL FLUID DEFLECTING STRUCTURES        AND PARTICLE RETAINING STRUCTURES, naming Edward S. Boyden;        Gregory J. Della Rocca; Daniel Hawkins; Roderick A. Hyde; Robert        Langer; Eric C. Leuthardt; Terence Myckatyn; Parag Jitendra        Parikh; Dennis J. Rivet; Joshua S. Shimony; Michael A. Smith;        and Clarence T. Tegreene as inventors, filed 28 Sep. 2012 with        attorney docket no. 0411-002-009-000000, which is currently        co-pending.

RELATED APPLICATIONS

-   -   U.S. patent application Ser. No. To Be Assigned, entitled        ARTIFICIAL JOINT COMPONENTS INCLUDING MECHANIZED SYNOVIAL FLUID        DEFLECTING STRUCTURES AND PARTICLE RETAINING STRUCTURES, naming        Edward S. Boyden; Gregory J. Della Rocca; Daniel Hawkins;        Roderick A. Hyde; Robert Langer; Eric C. Leuthardt; Terence        Myckatyn; Parag Jitendra Parikh; Dennis J. Rivet; Joshua S.        Shimony; Michael A. Smith; and Clarence T. Tegreene as        inventors, filed 24 Oct. 2012 with attorney docket no.        0411-002-011-000000, is related to the present application.

The United States Patent Office (USPTO) has published a notice to theeffect that the USPTO's computer programs require that patent applicantsreference both a serial number and indicate whether an application is acontinuation, continuation-in-part, or divisional of a parentapplication. Stephen G. Kunin, Benefit of Prior-Filed Application, USPTOOfficial Gazette Mar. 18, 2003. The USPTO further has provided forms forthe Application Data Sheet which allow automatic loading ofbibliographic data but which require identification of each applicationas a continuation, continuation-in-part, or divisional of a parentapplication. The present Applicant Entity (hereinafter “Applicant”) hasprovided above a specific reference to the application(s) from whichpriority is being claimed as recited by statute. Applicant understandsthat the statute is unambiguous in its specific reference language anddoes not require either a serial number or any characterization, such as“continuation” or “continuation-in-part,” for claiming priority to U.S.patent applications. Notwithstanding the foregoing, Applicantunderstands that the USPTO's computer programs have certain data entryrequirements, and hence Applicant has provided designation(s) of arelationship between the present application and its parentapplication(s) as set forth above and in any ADS filed in thisapplication, but expressly points out that such designation(s) are notto be construed in any way as any type of commentary and/or admission asto whether or not the present application contains any new matter inaddition to the matter of its parent application(s).

If the listings of applications provided above are inconsistent with thelistings provided via an ADS, it is the intent of the Applicant to claimpriority to each application that appears in the Priority Applicationssection of the ADS and to each application that appears in the PriorityApplications section of this application.

All subject matter of the Priority Applications and the RelatedApplications and of any and all parent, grandparent, great-grandparent,etc. applications of the Priority Applications and the RelatedApplications, including any priority claims, is incorporated herein byreference to the extent such subject matter is not inconsistentherewith.

SUMMARY

In some aspects, an artificial joint prosthesis includes: a bone-facingsurface of an artificial joint prosthesis, the bone-facing surfaceconfigured to face a bone-prosthesis interface in vivo; a non-contactsurface of the artificial joint prosthesis, the non-contact surfaceadjacent to the bone-facing surface of the artificial joint prosthesis;at least one fluid deflection structure positioned adjacent to thenon-contact surface, the fluid deflection structure positioned todeflect synovial fluid away from the bone-prosthesis interface in vivo;and a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.

In some aspects, an artificial hip prosthesis includes: a bone-facingsurface of a hip joint prosthesis, the bone-facing surface configured toface a bone-prosthesis interface in vivo; a non-contact surface of thehip joint prosthesis, the non-contact surface adjacent to thebone-facing surface of the hip joint prosthesis; at least one fluiddeflection structure positioned adjacent to the non-contact surface, thefluid deflection structure positioned to deflect synovial fluid awayfrom the bone-prosthesis interface in vivo; and a mechanism attached tothe fluid deflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo.

In some aspects, an artificial knee prosthesis includes: a bone-facingsurface of a knee joint prosthesis, the bone-facing surface configuredto face a bone-prosthesis interface in vivo; a non-contact surface ofthe knee joint prosthesis, the non-contact surface adjacent to thebone-facing surface of the knee joint prosthesis; at least one fluiddeflection structure positioned adjacent to the non-contact surface, thefluid deflection structure positioned to deflect synovial fluid awayfrom the bone-prosthesis interface in vivo; and a mechanism attached tothe fluid deflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo.

In some aspects, an artificial shoulder prosthesis includes: abone-facing surface of a shoulder joint prosthesis, the bone-facingsurface configured to face a bone-prosthesis interface in vivo; anon-contact surface of the shoulder joint prosthesis, the non-contactsurface adjacent to the bone-facing surface of the shoulder jointprosthesis; at least one fluid deflection structure positioned adjacentto the non-contact surface, the fluid deflection structure positioned todeflect synovial fluid away from the bone-prosthesis interface in vivo;and a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.

In addition to the foregoing, other aspects are described in the claims,drawings, and text forming a part of the disclosure set forth herein.The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the drawings and the followingdetailed description.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a artificial hip joint in cross-section.

FIG. 2 depicts an artificial hip joint as in FIG. 1, with the joint bentas during physiological use.

FIG. 3 shows an artificial hip joint as in FIG. 1, in an external view.

FIG. 4 illustrates an artificial hip joint as in FIG. 2, in an externalview.

FIG. 5 depicts components of an artificial hip joint.

FIG. 6 shows a femoral component of an artificial hip joint.

FIG. 7A illustrates a femoral component of an artificial hip joint, witha plurality of fluid deflection structures attached.

FIG. 7B shows a closer view of a fluid deflection structure attached tothe femoral component of an artificial hip joint.

FIG. 8 depicts an external, frontal view of an artificial knee joint.

FIG. 9 shows a side view of an artificial knee joint as in FIG. 8.

FIG. 10 illustrates an artificial shoulder joint.

FIG. 11 depicts an artificial hip joint in cross-section.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part hereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. The illustrative embodiments described in thedetailed description, drawings, and claims are not meant to be limiting.Other embodiments may be utilized, and other changes may be made,without departing from the spirit or scope of the subject matterpresented here.

Artificial joint prostheses are used as a surgical therapeuticsubstitute for joint components that are damaged, such as due to injuryor osteoarthritis. The goals of surgical implantation of artificialjoint prostheses generally include improving joint function andalleviating pain. Although these surgeries have a high success rate,there is some risk over time that an artificial joint prosthesis canfail. Failure of artificial prosthetic joints can require furthersurgery, with associated costs and morbidity for the patient. Oneclinically significant type of artificial joint failure is associatedwith loosening of the prosthesis at the bone interface, includingosteolysis and related damage to the bone.

Artificial joint prosthesis failure related to loosening of theprosthesis at the bone interface can have significant adverse clinicalconsequences. Patients can experience pain and reduced mobility, forexample, which can pose a problem for patients who are otherwise active.In addition, artificial joint prosthesis failure related to loosening ofthe prosthesis can pose a particular problem in younger patients whohave many years of expected lifespan ahead of them, with the associatedneed to preserve bone mass and joint function for the future. Thenegative consequences of prosthesis failure related to loosening of theprosthesis can also increase the medical burden of patients withsecondary medical problems. For example, reduced mobility fromprosthetic joint failure can be a significant problem for a person whouses exercise to control their high blood pressure. In some cases,surgical revision is required to address prosthesis failure related toloosening of the prosthesis, with associated costs and morbidity to thepatient. Although surgical revision rates vary by the type of prosthesisused and patient subgroup, a recent study of hip prosthesis failurerates found 5 year revision rates ranging from 1.6% to 6.1% (Smith etal., “Failure rates of Stemmed Metal-on-metal Hip Replacements: Analysisof Data from the National Joint Registry of England and Wales,” TheLancet, 379:1199-1204 (2012), which is incorporated herein byreference).

Artificial joint prosthesis failure is associated in a significantnumber of cases with loosening of the prosthesis at the prosthesis-jointinterface or in the periprosthetic region due to loss of the adjacentbone. This is believed to be caused in part from osteolysis promoted bythe body's response to debris from the artificial joint prosthesis. See,e.g. Linden, “Longer Life for Artificial Joints,” Nature 487: 179-180,(2012): and U.S. Pat. No. 5,378,228 “Method and Apparatus for JointFluid Decompression and Filtration with Particulate Debris Collection,”to Schmalzried and Jasty, which are each incorporated herein byreference. Wear debris from the prosthesis surface coming into contactwith the bone-prosthesis interface has been implicated, for example, inloosening of the prosthesis and associated failure. Debris particles atthe prosthesis-bone interface can contribute to osteolysis and resultingprosthesis loosening with potential failure of the prosthesis. Debrisparticles within the synovial fluid can include, for example, one ormore of: cellular debris particles, particulates of bone and prosthesisgenerated during surgery, and particulates formed from wear of theartificial joint prosthesis. Some studies indicate that debris particlescan enter the prosthesis-bone interface region through increasedsynovial fluid pressure at the prosthesis-joint interface duringphysiological movement. Some studies indicate that debris particles canenter the prosthesis-bone interface region through increased synovialfluid flow rate against the prosthesis joint interface duringphysiological movement. Studies also indicate that both fluid pressureand flow rate at the prosthesis-joint interface due to prosthesismovement during physiological activities encourage debris particles toenter the prosthesis-bone interface, contributing to osteolysis andprosthesis failure. See: Smith et al., ibid.; Fahlgren et al., “FluidPressure and Flow as a Cause of Bone Resorption,” Acta Orthopaedica81(4):508-516 (2010): Bartlett et al., “In Vitro Influence of StemSurface Finish and Mantle Conformity on Pressure Generation in CementedHip Arthroplasty,” Acta Orthopaedica 80(2): 139-143 (2009): Bartlett etal., “The Femoral Stem Pump in Cemented Hip Arthroplasty: an In VitroModel,” Medical Engineering and Physics, 30: 1042-1048 (2008): Agarwal,“Osteolysis—Basic Science, Incidence and Diagnosis,” CurrentOrthopaedics 18: 220-231 (2004); Manley et al., “Osteolysis: a Diseaseof Access to Fixation Interfaces,” Clinical Orthopaedics and RelatedResearch 405:129-137 (2002); and Anthony et al., “Localized EndostealBone Lysis in Relation to the Femoral Components of Cemented Total HipArthroplasties,” British Journal of Bone and Joint Surgery, 72-B(6):971-979 (1990), which are each incorporated herein by reference. Seealso: US Patent Application No. 2003/0014122 and U.S. Pat. No.6,569,202, each titled “Tray and Liner for Joint Replacement System,” toWhiteside; US Patent Application No. 2005/0055101 “Endoprosthesis of theKnee and/or other Joints,” to Sifneos; and US Patent Application No.2004/0068322, “Reduced-Friction Artificial Joints and ComponentsTherefor” to Ferree, which are each incorporated herein by reference.

The artificial joint prosthesis components described herein includesynovial fluid deflecting structures configured to divert synovial fluidflow away from the prosthesis-bone interface. Each of the artificialjoints includes fluid deflecting structures that are attached to amechanism that moves the fluid deflecting structures to direct synovialfluid away from the bone-prosthesis interface in vivo. In someembodiments, the artificial joint prosthesis components described hereininclude fluid deflecting structures configured to divert synovial fluidflow away from the prosthesis-bone interface with attached mechanism(s)as well as those without attached mechanism(s). In such embodiments, thefluid deflecting structures without attached mechanism(s) are configuredto work in combination with the fluid deflecting structures withattached mechanism(s) to divert synovial fluid flow away from theprosthesis-bone interface. The combination of fluid deflectingstructures with and without attached mechanisms, as a whole, areconfigured to divert synovial fluid flow and high pressure away from theprosthesis-bone interface. The artificial joint prosthesis componentsdescribed herein include synovial fluid deflecting structuresconfigured, in combination with the attached mechanisms, to divertsynovial fluid and debris particles within the fluid away from theprosthesis-bone interface. The synovial fluid deflecting structures ofthe artificial joint prosthesis components described herein are alsoconfigured, in combination with any attached mechanism(s), to decreasethe transient synovial fluid pressure at the prosthesis-bone interfaceduring physiological activities. The reduction of synovial fluid flow aswell as transient pressure at the bone-prosthesis interface will lead toa reduction of debris particles entering the prosthesis-bone interfaceduring physiological movement. This will decrease the risk of osteolysisrelated to wear debris particles at the prosthesis-bone interface,thereby reducing the risk of prosthesis failure and the need forrevision surgery with its associated costs and morbidity. In someembodiments, the prosthesis structures will include additional chemicalinhibitors of osteolysis (see, e.g. Linden, ibid, and Mediero et al.,“Adenosine A_(2A) Receptor Activation Prevents Wear Particle-InducedOsteolysis,” Science Translational Medicine 4 (135ra65) (2012), whichare each incorporated herein by reference).

The artificial joint prosthesis components described herein includesynovial fluid deflecting structures configured to deflect synovialfluid flow away from the bone-prosthesis interface as well as tomitigate the transient increase in synovial fluid pressure at thebone-prosthesis interface during physiological movement (see, e.g. FIGS.2 and 4). Each of the synovial fluid deflecting structures is attachedto a mechanism configured to move the synovial fluid deflectionstructure, and thus to direct synovial fluid away from thebone-prosthesis interface in vivo. Each of the synovial fluid deflectingstructures is positioned adjacent to a non-contact surface of theartificial joint prosthesis. In some embodiments, there are synovialfluid deflecting structures positioned on one component of an artificialjoint prosthesis. In some embodiments, there are synovial fluiddeflecting structures positioned on two or more components of anartificial joint prosthesis, with the synovial fluid deflectingstructures configured to work in combination during relative motion ofthe two or more components of an artificial joint prosthesis during invivo use (see, e.g. FIGS. 1-4). In some embodiments, there are synovialfluid deflecting structures with attached mechanisms configured toinduce angular momentum in the synovial fluid during physiologicalmovement. The induced angular momentum of the synovial fluid results indeflection of the synovial fluid flow away from the bone-prosthesisinterface, and reduced transient pressure at the bone-prosthesisinterface during physiological movement during in vivo use. In someembodiments, there are synovial fluid deflecting structures positionedon one or more of the joint components with attached mechanismsconfigured to convert the force from the joint motion on the synovialfluid during physiological movement into a resulting synovial fluid flowin an inclined or orthogonal direction relative to the original synovialfluid flow. The converted inclined or orthogonal direction of thesynovial fluid results in deflection of the synovial fluid flow awayfrom the bone-prosthesis interface, and reduced transient pressure atthe bone-prosthesis interface during physiological movement during invivo use. The specific positioning, size, shape and configuration of thesynovial fluid deflecting structures on the artificial joint prosthesiscomponents will vary depending on the embodiment, including the specifictype of artificial joint prosthesis, its size, the size of theassociated joint in vivo, and expected physiological forces on theassociated synovial fluid when the artificial joint prosthesis is usedin vivo. Similarly, the attached mechanisms will vary depending on theembodiment, including the specific type of artificial joint prosthesis,the size of the prosthesis, the size and configuration of the fluiddeflection structures, and the expected force of the synovial fluid flowin vivo.

The material used to fabricate a synovial fluid deflection structure andan attached mechanism will vary depending on the embodiment. Factors inthe selection of materials for a fluid deflection structure and anattached mechanism include: cost of the materials, size of the fluiddeflection structure, shape of the fluid deflection structure,flexibility of the fluid deflection structure under the estimatedphysiological pressure of synovial fluid in a given embodiment, andcompatibility of the fluid deflection structure with other components ofthe prosthetic implant. Materials used to fabricate a fluid deflectionstructure and an attached mechanism will be part of the prostheticjoint, and therefore should be suitable for implantation into a body(e.g. low toxicity and non-inflammatory). Materials used to fabricate afluid deflection structure and an attached mechanism should be expectedto be durable throughout the anticipated duration of use of theprosthetic joint, for example no less than 10 years of routinephysiological use in vivo. Materials suitable for fabrication of asynovial fluid deflection structure include, for example, polypropyleneand silicone.

Although the artificial joint prostheses are described herein primarilyin reference to humans, in some embodiments the artificial jointprostheses as described herein will also have applicability inveterinary medicine. For example, aspects of the artificial hip jointprosthesis as described herein (see, e.g. FIGS. 1-7 and associated text)have applicability in hip joint replacements in domestic animals, suchas dogs and cats.

In some embodiments, an artificial joint prosthesis includes: abone-facing surface of the artificial joint prosthesis, the bone-facingsurface configured to face a bone-prosthesis interface in vivo; anon-load bearing surface of the artificial joint prosthesis, thenon-load bearing surface adjacent to the bone-facing surface of theartificial joint prosthesis; at least one fluid deflection structurepositioned adjacent to the non-load bearing surface; and a mechanismattached to the fluid deflection structure, the mechanism operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone-prosthesis interface in vivo. As used herein, the “non-loadbearing surface” of an artificial joint prosthesis is a surface expectedto not bear a significant load, such as the person's mass, duringroutine movement utilizing normal physiological activities. For example,the edge of a acetabular liner in a hip joint prosthesis is generallyexpected to be non-load bearing during routine movement utilizing normalphysiological activity, although the edge of an acetabular liner in ahip joint prosthesis may become load bearing during an extremephysiological event, such as hip joint dislocation. For example, theedge of a humerus component in a shoulder joint prosthesis is generallyexpected to be non-load bearing during routine movement utilizing normalphysiological activity, although the edge of a humerus component in ashoulder joint prosthesis may become load bearing during an extremephysiological event, such as shoulder joint dislocation. The specificregions of an artificial joint prosthesis that would be expected to be a“non-load bearing surface” depend on the specific type of artificialjoint, its size and position during in vivo use.

In some embodiments, an artificial joint prosthesis includes: abone-facing surface of an artificial joint prosthesis, the bone-facingsurface configured to face a bone-prosthesis interface in vivo; anon-contact surface of the artificial joint prosthesis, the non-contactsurface adjacent to the bone-facing surface of the artificial jointprosthesis; at least one fluid deflection structure positioned adjacentto the non-contact surface, the fluid deflection structure positioned todeflect synovial fluid away from the bone-prosthesis interface in vivo;and a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo. As usedherein, a “non-contact surface” of an artificial joint prosthesis refersto a surface of a component of the artificial joint prosthesis that isexpected to not come into contact with the bone and also to not comeinto contact with a surface of another component of the artificial jointprosthesis during normal physiological use of the artificial jointprosthesis in vivo. Specific examples of non-contact surfaces are shownin the Figures, and discussed in the relevant text associated with eachFigure. The artificial joint prosthesis can include at least one of: ahip joint prosthesis, a knee joint prosthesis, a shoulder jointprosthesis, an ankle joint prosthesis, or an elbow joint prosthesis.See, for example, FIGS. 1-10 and associated text. The non-contactsurface of the artificial joint prosthesis is a surface of theprosthesis that is expected to not have contact with bone surfaces ofthe joint or other surfaces of the joint prosthesis during routinephysiological movement in vivo. For example, FIG. 5 depicts componentsof a hip prosthesis including fluid deflection structures positionedadjacent to the non-contact surfaces. In some embodiments wherein theprosthesis is for a hip joint, the non-contact surface of the artificialjoint prosthesis can include at least one of: a region of a shell of aacetabular component of a hip joint prosthesis; a region of a liner of aacetabular component of a hip joint prosthesis; a region of a head of afemoral component of a hip joint prosthesis, or a region of a stem of afemoral component of a hip joint prosthesis. In some embodiments whereinthe prosthesis is for a knee joint, the non-contact surface of theartificial joint prosthesis can include at least one of: a region of afemoral component of a knee joint prosthesis; a region of a tibialspacer of a knee joint prosthesis; a region of a tibial component of aknee joint prosthesis; or a region of a component of a patellarcomponent of a knee joint prosthesis. In some embodiments wherein theprosthesis is for a shoulder joint, the non-contact surface of theartificial joint prosthesis can include at least one of: a region of ahumeral stem of a shoulder joint prosthesis; a region of a humeralspacer of a shoulder joint prosthesis; a region of a humeral head of ashoulder joint prosthesis; or a region of a glenoid component of ashoulder joint prosthesis.

In some embodiments, an artificial joint prosthesis includes at leastone fluid deflection structure positioned adjacent to the non-contactsurface with a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo, whereinthe at least one fluid deflection structure includes at least one flangestructure positioned to extend from the non-contact surface. The fluiddeflection structure is configured to deflect synovial fluid asdescribed herein. In some embodiments, a fluid deflection structurepositioned adjacent to the non-contact surface is configured as at leastone flange structure positioned to extend from the non-contact surface.For example, a flange structure can be configured as a projecting rim orcollar from the non-contact surface. For example, a flange structure canbe configured as one or more ridges positioned adjacent to thenon-contact surface. The relative size and shape of the flange structurewill vary by the specific type of artificial joint (e.g. hip, knee,shoulder), the flexibility of the material used in construction of theflange structure, and the size of the artificial joint (e.g. relative tothe size of the patient and the size of the implant required fortherapeutic correction of their joint). In some embodiments, the flangestructure can form a ring to encircle the entirety of a non-contactsurface. In some embodiments, the flange structure can form a rim orcollar along the entirety of a non-contact surface, or along a partialedge of a non-contact surface. In some embodiments, the flange structurecan include a series of smaller structures, such as a plurality ofprojections.

The at least one flange structure can be positioned to extend from thenon-contact surface at an angle predicted to mitigate synovial fluidflow rate and transient fluid pressure at the location of thebone-prosthesis interface. The angle of a flange structure projectingfrom the non-contact surface suitable to deflect synovial fluid flow andreduce transient synovial fluid pressure at the bone-prosthesisinterface will depend on the configuration of the artificial jointprosthesis in a specific embodiment, including, for example, the numberof flange structures, their relative positioning on the artificial jointprosthesis, the size and shape of the flange structures, the size andposition of the attached mechanism, and the size of the joint in vivo.For example, in some embodiments the at least one flange structure canbe positioned to extend from the non-contact surface at an anglesubstantially between 10 degrees and 80 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theartificial joint prosthesis. For example, in some embodiments the atleast one flange structure can be positioned to extend from thenon-contact surface at an angle substantially between 100 degrees and170 degrees of a plane established by the contact surface and relativeto the bone-facing surface of the artificial joint prosthesis. Forexample, in some embodiments the at least one flange structure can bepositioned to extend from the mechanism at the non-contact surface at asubstantially right angle from a plane established by the contactsurface and relative to the bone-facing surface of the artificial jointprosthesis.

In some embodiments wherein the at least one fluid deflection structurewith an attached mechanism positioned adjacent to the non-contactsurface includes at least one flange structure positioned to extend fromthe non-contact surface, the at least one flange structure can include afirst end connected to the non-contact surface by the attached mechanismand a second end distal to the non-contact surface, wherein the flangestructure is widest at the first end and narrowest at the second end.See, for example, FIGS. 1-4. The at least one flange structure caninclude at least one flange structure with a first end connected to thenon-contact surface by the attached mechanism and a second end distal tothe non-contact surface, wherein the flange structure tapers from awidest point at the first end to a narrow point at the second end. See,for example, FIGS. 1-4. In some embodiments, the at least one fluiddeflection structure includes at least one flange structure with acurvilinear structure. For example, the flange structure can include athin, substantially curved structure, such as a crescent moon-shapedstructure. See, for example, FIGS. 1-4. In some embodiments, the atleast one fluid deflection structure includes at least one flangestructure with a significantly straight structure. See, for example,FIG. 5.

In some embodiments, the at least one fluid deflection structure, withan attached mechanism, positioned adjacent to the non-contact surfaceincludes at least one fluid deflection structure with a first endpositioned adjacent to the non-contact surface and a second end distalto the non-contact surface. In some embodiments, the at least one fluiddeflection structure positioned on the non-contact surface includes aplurality of linear projections. For example, the linear projections canbe hair-like or ciliated. See, for example, FIG. 5. The linearprojections are positioned adjacent to the non-contact surface at anangle appropriate to divert part of the flow of synovial fluid away fromthe bone-prosthesis interface, and to reduce synovial fluid pressure atthe bone-prosthesis interface during physiological movement. The size,shape, and attachment angle of the linear projections will, therefore,vary by the specific embodiment. For example, in embodiments wherein theat least one fluid deflection structure includes a plurality of linearprojections, the linear projections can be positioned to extend from thenon-contact surface at an angle substantially between 10 degrees and 80degrees of a plane established by the contact surface and relative tothe bone-facing surface of the artificial joint prosthesis. For example,in embodiments wherein the at least one fluid deflection structureincludes a plurality of linear projections, the plurality of linearprojections can be positioned to extend from the non-contact surface atan angle substantially between 100 degrees and 170 degrees of a planeestablished by the contact surface and relative to the bone-facingsurface of the artificial joint prosthesis. For example, in embodimentswherein the at least one fluid deflection structure includes a pluralityof linear projections, the plurality of linear projections can bepositioned to extend from the non-contact surface at an substantiallyright angle from a plane established by the contact surface and relativeto the bone-facing surface of the artificial joint prosthesis.

The at least one fluid deflection structure positioned adjacent to thenon-contact surface is positioned relative to the non-contact surface atan angle appropriate to divert part of the flow of synovial fluid awayfrom the bone-prosthesis interface, and to reduce synovial fluidpressure at the bone-prosthesis interface during physiological movement.The size, shape, and attachment angle of the at least one fluiddeflection structure will, therefore, vary by the specific embodiment.Some embodiments include at least one fluid deflection structureattached to a single component of the artificial joint prosthesis. Someembodiments include at least two components of the artificial jointprosthesis, each of which include at least one fluid deflectionstructure positioned adjacent to a non-contact surface of the artificialjoint prosthesis. For example, in some embodiments the at least onefluid deflection structure includes a substantially straight fluiddeflection structure. For example, in some embodiments the at least onefluid deflection structure includes a substantially curved fluiddeflection structure.

Similarly, the rigidity of a synovial fluid deflection structure willvary depending on the embodiment, relative to factors such as thespecific type of joint, its size, the expected flow dynamics of synovialfluid through the joint during in vivo use, the position of the synovialfluid deflection structure on the prosthesis, the type and potentialforce utilized by the attached mechanism, and the shape of the synovialfluid deflection structure. In some embodiments, the at least one fluiddeflection structure positioned adjacent to the non-contact surface isconfigured to be substantially rigid at physiological conditions whenthe artificial joint is utilized in vivo. In some embodiments, the atleast one fluid deflection structure positioned adjacent to thenon-contact surface is configured to be flexible at physiologicalconditions when the artificial joint is utilized in vivo. In someembodiments, the at least one fluid deflection structure positionedadjacent to the non-contact surface is configured to flex to a degreesufficient to permit a larger synovial fluid flow rate away from thebone-prosthesis interface during periods of increased synovial fluidpressure in the region of the non-contact surface when the artificialjoint is utilized in vivo at physiological conditions, and to permit asmaller synovial fluid flow rate away from the bone-prosthesis interfaceduring periods of reduced synovial fluid pressure when the artificialjoint is utilized in vivo at physiological conditions. In someembodiments, the at least one fluid deflection structure positionedadjacent to the non-contact surface is configured to flex to a degreesufficient to permit an increased synovial fluid flow rate away from thebone-prosthesis interface in response to increased fluid pressure in aregion adjacent to the bone-prosthesis interface.

The mechanism attached to the fluid deflection structure and operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone-prosthesis interface in vivo can be configured in differentforms, depending on the embodiment. For example, the mechanism can beattached to the fluid deflection structure and positioned on the surfaceof the prosthesis. For example, the mechanism and attached fluiddeflection structure can be positioned adjacent to the non-contactsurface of the prosthesis, such as with epoxy, glue, or other adhesives.For example, the mechanism with the attached fluid deflection structurecan be configured to mate with a corresponding surface on thenon-contact region of the prosthesis. In some embodiments, the mechanismattached to the fluid deflection structure is substantially enclosedwithin the artificial joint prosthesis. For example, the mechanismattached to the fluid deflection structure can be substantially enclosedwithin a cavity or groove in the non-contact region of the prosthesis.For example, the mechanism attached to the fluid deflection structurecan be substantially enclosed within an extension of the prosthesisconfigured to attach the mechanism. The mechanism can be a micromachine,for example one in the size range of 100 nanometers (nm) to 100micrometers (μm) in diameter. The mechanism can be a MEMS device, forexample with a size range of 20 μm to 1 millimeter (mm) in diameter.

The mechanism attached to the fluid deflection structure and operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone-prosthesis interface in vivo can be of a variety of types,depending on the embodiment. Factors to be used in the selection of amechanism include: the force on the fluid deflection structure desiredto deflect the fluid; the size, shape and flexibility of the fluiddeflection structures; the size of the mechanism; the cost of themechanism; and the expected duration of use of the artificial jointprosthesis in vivo. In some embodiments, the mechanism attached to thefluid deflection structure includes an actuator attached to the fluiddeflection structure and configured to move the fluid deflectionstructure. For example, an actuator can include a hydraulic piston,which can be positioned within a cavity formed in the prosthesis. Inembodiments wherein the mechanism attached to the fluid deflectionstructure includes an actuator with a hydraulic piston, force from fluidflow against the fluid deflection structure can be transmitted to thepiston, with a resulting reverse force transmitted back to the fluiddeflection structure to drive movement of the fluid deflectionstructure. Some embodiments include a battery configured to provideenergy to the actuator. For example, the actuator can include anelectric motor which is connected to an attached battery.

In some embodiments, the mechanism attached to the fluid deflectionstructure includes piezoelectric material, the piezoelectric materialconfigured to drive movement of the at least one fluid deflectionstructure. For example, in some embodiments a piezoelectric materialattached to a fluid deflection structure can be configured to generateelectrical charge from the pressure force on the fluid deflectionstructure, and then store the electrical charge in an attached battery.The stored charge in the battery can then be utilized to drive the samefluid deflection structure, or a second fluid deflection structure, withan attached electric motor. Instead or in addition, the stored charge inthe battery can be utilized to drive the same fluid deflection structurethrough re-introduction of the electrical charge to the piezoelectricmaterial, with the resulting reverse piezoelectric effect resulting inpressure force on the fluid deflection structure due to the expansion ofthe piezoelectric material.

In some embodiments, the mechanism attached to the fluid deflectionstructure and operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo includesat least one magnetic actuator, the magnetic actuator configured todrive movement of the at least one fluid deflection structure.

Some embodiments include: an aperture in the non-contact surface of theartificial joint prosthesis; a substantially round cavity in theartificial joint prosthesis adjacent to the aperture; the mechanismincluding a substantially round element of a size and shape tocorrespond to the substantially round cavity, the substantially roundelement positioned within the substantially round cavity and configuredto move within the substantially round cavity; and the at least onefluid deflection structure attached to the substantially round elementand projecting through the aperture. For example, the mechanism can beconfigured with a substantially round external shape, of a size andshape to reversibly mate with the internal surface of the substantiallyround cavity in the artificial joint prosthesis. A mechanism with asubstantially round external shape within a substantially round cavitycan rotate in the cavity, with the resulting movement of a fluiddeflection structure attached to the mechanism and projecting through anaperture between the cavity and the external surface of the prosthesis.The mechanism can utilize the force transmitted by the joint fluidthrough the fluid deflection structure, such as through the operation ofa piezoelectric material or hydraulic piston, to drive further movementof the attached fluid deflection structure. The mechanism can beconfigured as a ball-like structure to rotate within the cavity inmultiple directions. The mechanism can be configured as a cylindricalstructure, with a corresponding cylindrical cavity, to rotatespecifically along the axis formed by the radius of the cylindricalstructure.

Some embodiments of an artificial joint prosthesis include: at least onefirst magnet attached to the artificial joint prosthesis; and at leastone second magnet attached to the fluid deflection structure, whereinthe mechanism attached to the fluid deflection structure is configuredto move in accord with a magnetic field established by the at least onefirst magnet. Some embodiments of an artificial joint prosthesisinclude: at least one first magnet attached to the artificial jointprosthesis; and at least one second magnet attached to the fluiddeflection structure, wherein the mechanism attached to the fluiddeflection structure is configured to allow the at least one secondmagnet to move the fluid deflection structure in accord with a magneticfield established by the at least one first magnet. The magnets can beconfigured as a mechanism attached to the fluid deflection structure,the mechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo. Themagnets can be configured to assist a mechanism attached to the fluiddeflection structure, the mechanism operable to move the fluiddeflection structure.

Some embodiments of an artificial joint prosthesis include at least twocomponents, each of which include at least one fluid deflectionstructure, and each of which include the mechanism attached to the fluiddeflection structure, each of the mechanisms operable to move each ofthe fluid deflection structures to direct synovial fluid away from thebone-prosthesis interface in vivo. For example, an artificial hipprosthesis can include a femoral component and an acetabular component,each of which include at least one fluid deflection structure with anattached mechanism, each of the mechanisms operable to move each of thefluid deflection structures to direct synovial fluid away from thebone-prosthesis interface in vivo during physiological use of theartificial hip joint.

For a more complete understanding of the embodiments, reference now ismade to the following descriptions taken in connection with theaccompanying drawings. The use of the same symbols in different drawingstypically indicates similar or identical items, unless context indicatesotherwise.

With reference now to FIG. 1, shown is an example of an artificial hipjoint prosthesis depicted in vivo in cross-section that serves as acontext for introducing one or more artificial joint prosthesesincluding fluid deflecting structures as described herein. Theartificial hip joint prosthesis depicted in FIG. 1 is depicted incross-section in vivo in a resting, or not significantly physiologicallyflexed, position. The cross-section view depicted in FIG. 1 is asubstantially planar view of a vertical cross-section through the hipjoint. The embodiment illustrated in FIG. 1 depicts a hip jointprosthesis including: a bone-facing surface of a hip joint prosthesis,the bone-facing surface configured to face a bone-prosthesis interfacein vivo; a non-contact surface of the hip joint prosthesis, thenon-contact surface adjacent to the bone-facing surface of the hip jointprosthesis; at least one fluid deflection structure positioned adjacentto the non-contact surface, the fluid deflection structure positioned todeflect synovial fluid away from the bone-prosthesis interface in vivo;and a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.

FIG. 1 illustrates a hip joint prosthesis 100 in vivo, with prostheticcomponents including an acetabular shell 170, and acetabular liner 175,and a femoral component. The femoral component includes a femoral headcomponent 182 and a femoral stem component 187. In some contexts, anacetabular shell 170 is referred to as an acetabular cup. A synovialmembrane 190 forms the boundary of the joint region that includessynovial fluid. The prosthetic components 170, 175, 182, 187 arerespectively attached to a pelvic bone 160 and femur 150. The acetabularliner 175 includes a bone-facing surface 110. The acetabular shell 170includes a bone-facing surface 112. The femoral stem component 187includes a bone-facing surface 115. The bone-facing surfaces 110, 112,115 of the prosthetic components 170, 175, 187 in contact with the boneform bone-prosthesis interfaces 120 in vivo.

The hip joint prosthesis 100 depicted in FIG. 1 includes several regionswith non-contact surfaces. As shown in FIG. 1, the acetabular liner 175includes an edge region with a non-contact surface 130. The non-contactsurface 130 of the acetabular liner 175 is a surface of the acetabularliner 175 that is predicted to not come in contact with the bone (e.g.the pelvis 160) or a surface of another component of the artificial hipjoint (e.g. the femoral head 182) during normal physiological use invivo. The non-contact surface 130 of the acetabular liner 175 includessynovial fluid deflecting structures 140 positioned adjacent to thesurface. In some embodiments, the non-contact surface of an artificialhip prosthesis includes an edge region of a liner of a acetabularcomponent of the hip joint prosthesis. In some embodiments, thenon-contact surface of an artificial hip prosthesis includes an edgeregion of a shell of a acetabular component of the hip joint prosthesis.Also as shown in FIG. 1, the femoral stem 187 includes a region with anon-contact surface 135. The non-contact surface 135 of the femoral stem187 is a surface of the femoral stem 187 that is predicted to not comein contact with the bone (e.g. the femur 150) or a surface of anothercomponent of the artificial hip joint (e.g. the acetabular liner 175)during normal physiological use in vivo. The non-contact surface 135 ofthe femoral stem 187 includes synovial fluid deflecting structures 145positioned adjacent to the surface. In some embodiments, the non-contactsurface of an artificial hip prosthesis includes an edge region of ahead of a femoral component of the hip joint prosthesis (see, e.g. FIG.5). In some embodiments, the non-contact surface of an artificial hipprosthesis includes an edge region of a stem of a femoral component ofthe hip joint prosthesis.

FIG. 1 illustrates that some embodiments include a plurality of fluiddeflection structures 140, 145, with attached mechanisms, positioned onmore than one non-contact surface 130, 135 of the artificial hipprosthesis. In some embodiments, only one region with a non-contactsurface has adjacent one or more fluid deflection structures andassociated mechanisms. For example, in some embodiments, fluiddeflection structures 140 and associated mechanisms are positionedadjacent to only the non-contact surface 130 of the acetabular liner175. For example, in some embodiments, fluid deflection structures 145and associated mechanisms are positioned adjacent to only thenon-contact surface 135 of the femoral stem 187.

In some embodiments, the at least one fluid deflection structure, withattached mechanisms, positioned on the non-contact surface of anartificial hip prosthesis includes at least one flange structurepositioned to extend from the non-contact surface. The flange structureis of a size and shape to deflect synovial fluid flow away from one ormore of the bone-prosthesis interfaces 120 in vivo. The flange structureis of a size and shape to mitigate synovial fluid pressure at one ormore of the bone-prosthesis interfaces 120 in vivo during physiologicaluse of the joint. For example, in some embodiments, the at least oneflange structure is positioned to extend from the non-contact surface atan angle substantially between 10 degrees and 80 degrees of a planeestablished by the contact surface and relative to the bone-facingsurface of the hip joint prosthesis. For example, in some embodiments,the at least one flange structure is positioned to extend from thenon-contact surface at an angle substantially between 100 degrees and170 degrees of a plane established by the contact surface and relativeto the bone-facing surface of the hip joint prosthesis. For example, insome embodiments, the at least one flange structure is positioned toextend from the non-contact surface at a substantially right angle froma plane established by the contact surface and relative to thebone-facing surface of the hip joint prosthesis. The flange structurecan include a first end adjacent to the non-contact surface and a secondend distal to the non-contact surface, wherein the flange structure iswidest at the first end and narrowest at the second end. The flangestructure can include a first end connected to the non-contact surfaceand a second end distal to the non-contact surface, wherein the flangestructure tapers from a widest point at the first end to a narrow pointat the second end. The flange structure can include at least one flangestructure with a curvilinear structure. The flange structure can includeat least one flange structure with a substantially flat or linearstructure when not under pressure from synovial fluid, and a curvilinearstructure when under pressure.

As shown in FIG. 1, a fluid deflection structure 140, 145 can include afirst end adjacent to the non-contact surface and a second end distal tothe non-contact surface. In some embodiments, a fluid deflectionstructure can include a substantially planar structure. In someembodiments, a fluid deflection structure can include a tapered orangular structure. In some embodiments, a fluid deflection structure caninclude a collar structure around an edge of a non-contact surface. Asshown in FIG. 1, some embodiments include a plurality of fluiddeflection structures 140, 145. Some embodiments include at least oneacetabular liner 175, wherein the acetabular liner 175 includes at leastone fluid deflection structure 140 positioned adjacent to thenon-contact surface 130; and at least one femoral stem 187, wherein thefemoral stem 187 includes at least one fluid deflection structure 145positioned adjacent to the non-contact surface 135.

In some embodiments, a fluid deflection structure can include aplurality of linear projections. For example, a fluid deflectionstructure can include one or more hair-like or ciliated structures. Theplurality of linear projections are of a size and shape so that thelinear projections, in the aggregate, deflect synovial fluid flow awayfrom one or more of the bone-prosthesis interfaces 120 in vivo. Thespecific size and number of linear projections will depend on theembodiment, relative to factors including the size of the joint, theestimated synovial fluid pressure in the joint during physiological use,and the flexibility of the material used to fabricate the fluiddeflection structure including a plurality of linear projections. Insome embodiments, the plurality of linear projections are positioned toextend from the non-contact surface at an angle substantially between 10degrees and 80 degrees of a plane established by the contact surface andrelative to the bone-facing surface of the hip joint prosthesis. In someembodiments, the plurality of linear projections are positioned toextend from the non-contact surface at an angle substantially between100 degrees and 170 degrees of a plane established by the contactsurface and relative to the bone-facing surface of the hip jointprosthesis. In some embodiments, the plurality of linear projections arepositioned to extend from the non-contact surface at an substantiallyright angle from a plane established by the contact surface and relativeto the bone-facing surface of the hip joint prosthesis.

Some embodiments include at least one fluid deflection structurepositioned adjacent to the non-contact surface wherein the at least onefluid deflection structure includes a substantially straight fluiddeflection structure. The substantially straight fluid deflectionstructure can be, for example, substantially linear or substantiallyplanar. The substantially straight fluid deflection structure can be,for example, substantially straight in the absence of synovial fluidpressure but flex or bend in the presence of synovial fluid pressureduring in vivo use of the artificial hip joint. Some embodiments includeat least one fluid deflection structure positioned on the non-contactsurface including a substantially curved fluid deflection structure. Thesubstantially curved fluid deflection structure can further curve orbend in the presence of synovial fluid pressure during in vivo use ofthe artificial hip joint.

In some embodiments, a fluid deflection structure of any initial shapecan be configured to be substantially rigid at physiological conditionswhen the artificial joint is utilized in vivo. For example, a fluiddeflection structure can be fabricated from a material in a suitablesize and shape that is expected to be substantially rigid during in vivouse of the artificial hip joint prosthesis. The rigidity of a fluiddeflection structure may be desirable, for example to enhance angularmomentum in the synovial fluid. In some embodiments, the attachedmechanism includes a projection that serves as a central stabilizingstructure within the fluid deflection structure. For example, themechanism can operate to move an attached rod, with the rod serving as acentral stabilizing structure within the fluid deflection structure. Therod may be fabricated a substantially rigid material, with the remainderof the fluid deflection structure fabricated from a substantiallyflexible material.

In some embodiments, a fluid deflection structure of any initial shapecan be configured to be flexible at physiological conditions when theartificial joint is utilized in vivo. For example, a fluid deflectionstructure can be fabricated from a material in a suitable size and shapethat is expected to be flexible during in vivo use of the artificial hipjoint prosthesis. The flexibility of a fluid deflection structure may bedesirable, for example, to convert the fluid pressure resulting fromjoint motion in one direction into synovial fluid motion in an inclinedor orthogonal direction during use of the artificial hip jointprosthesis. For example, in some embodiments the at least one fluiddeflection structure positioned on the non-contact surface can beconfigured to flex to a degree sufficient to permit a larger synovialfluid flow rate away from the bone-prosthesis interface during periodsof increased synovial fluid pressure in the region of the non-contactsurface when the artificial joint is utilized in vivo at physiologicalconditions, and to permit a smaller synovial fluid flow rate away fromthe bone-prosthesis interface during periods of reduced synovial fluidpressure when the artificial joint is utilized in vivo at physiologicalconditions. For example, in some embodiments the at least one fluiddeflection structure positioned on the non-contact surface is configuredto flex to a degree sufficient to permit an increased synovial fluidflow rate away from the bone-prosthesis interface in response toincreased fluid pressure in a region adjacent to the bone-prosthesisinterface.

FIG. 1 depicts each of the fluid deflection structures 140 positionedadjacent to the non-contact surface 130 and attached to a mechanism 143.Each of the mechanisms 143 is configured to fit within a cavity 173 inthe acetabular liner 175. Each cavity 173 in the acetabular liner 175 ispositioned adjacent to the non-contact surface 130 of the acetabularliner 175, with an aperture connecting the cavity 173 and thenon-contact surface 130. In the embodiment illustrated, no mechanismsare attached to the fluid deflecting structures 145 positioned adjacentto the non-contact surface 135 in the femoral stem component 187. Thefluid deflecting structures 145 positioned adjacent to the non-contactsurface 135 in the femoral stem component 187 are attached directly tothe adjacent non-contact surface 135. Some embodiments includemechanisms attached to the fluid deflecting structures positionedadjacent to all of the non-contact surfaces of an artificial hip jointprosthesis. Some embodiments include mechanisms attached to the fluiddeflecting structures positioned adjacent to less than all, or a subset,of the non-contact surfaces of an artificial hip joint prosthesis. Themechanisms can include, for example, electric motors, piezoresistentcomponents, hydraulic pistons, and magnetic components as discussedherein. A particular embodiment can include mechanisms including thesame or different components from each other. A particular embodimentcan include mechanisms operating under the same or different principlesfrom each other, including forces moving the attached fluid deflectingstructure(s), the flexibility of the attached fluid deflectingstructure(s), and the size of the attached fluid deflectingstructure(s).

FIG. 2 illustrates aspects of the artificial hip joint prosthesisembodiment as shown in FIG. 1. The artificial hip joint prosthesis 100depicted in FIG. 2 is depicted in cross-section in vivo in a flexed orbent position. As in FIG. 1, the view depicted in FIG. 2 is asubstantially planar view of a vertical cross-section through the hipjoint in vivo. As illustrated in FIG. 2, the artificial hip jointprosthesis 100 includes an acetabular shell 170, an acetabular liner 175and a femoral component including a femoral head 182 and femoral stem187. FIG. 2 depicts the joint in a flexed position, which is expected toresult in a transient increase in synovial fluid pressure at thebone-prosthesis interface regions put into closer proximity during thejoint repositioning. For example, FIG. 2 illustrates that regions of thenon-contact surface 130A of the acetabular liner 175 and a region of thenon-contact surface 135A of the femoral stem 187 are being placed incloser proximity due to the joint repositioning (e.g. relative to thejoint position illustrated in FIG. 1). Correspondingly, FIG. 2 showsthat regions of the non-contact surface 130B of the acetabular liner 175and a region of the non-contact surface 135B of the femoral stem 187 aremoved away from each other due to the joint repositioning (e.g. relativeto the joint position illustrated in FIG. 1).

For a transient period during and immediately after the joint flexing orbending from the position illustrated in FIG. 1 to the positionillustrated in FIG. 2, there is an increase in synovial fluid pressurein the region between the non-contact surface 130A of the acetabularliner 175 and a region of the non-contact surface 135A of the femoralstem 187. This results in an increased synovial fluid flow across thejoint, as illustrated by the dotted arrows across the artificial joint100 in FIG. 2. The joint bending, and the associated localized synovialfluid pressure increase, results in the flexing of the fluid deflectingstructures 140A attached to the non-contact surface 130A of theacetabular liner 175. The joint bending, and the associated localizedsynovial fluid pressure increase, also results in the flexing of thefluid deflecting structures 145A attached to the non-contact surface135A of the femoral stem 187. The fluid deflecting structures 140 B,145B attached to the non-contact surfaces 130B, 135B of the acetabularliner 175 and the femoral stem 187 not subject to increased synovialfluid pressure do not bend or flex in the same manner as the fluiddeflecting structures 140A, 145A subject to the localized synovial fluidpressure increase associated with the joint bending.

Some embodiments include mechanisms attached to the fluid deflectingstructures that are configured to respond to increases in fluidpressure, such as through normal physiological joint movement. Forexample, some embodiments include a piezoelectric element within themechanism, and a rod extending from the fluid deflecting structurethrough the mechanism, the rod configured to transmit pressure from thefluid to the piezoelectric element. The transient pressure increase inthe joint at that location, transmitted from the joint fluid through thefluid deflection structure to the mechanism, will result in a localizedeffect on the mechanism subject to fluid pressure at a given time.Correspondingly, a transient decrease in fluid pressure will result indecreased pressure on the mechanism. The changes in joint fluid pressureduring physiological movement of the joint are expected to be transientand localized within the joint, with corresponding effects on fluiddeflection structures and attached mechanisms.

FIG. 2 illustrates fluid deflection structures 140A under highertransient fluid pressure than corresponding fluid deflection structures140B in another region of the artificial joint. The mechanisms 143Aattached to the fluid deflection structures 140A under increasedtransient fluid pressure will respond to this pressure, for example withincreased opposing force on the fluid deflecting structures 140A. Thefluid deflection structures 140B under a reduced or lower transientfluid pressure have attached mechanisms 143B that will, similarly,respond to the reduced or lower transient fluid pressure in that regionof the joint.

FIG. 3 illustrates a hip joint prosthesis 100 in vivo, with prostheticcomponents including an acetabular liner 175, and a femoral stem 187.The embodiment depicted in FIG. 3 is similar to that shown in FIG. 1from an external viewpoint. Since the viewpoint of FIG. 3 is external,the mechanisms attached to the fluid deflection structures 140 are notvisible. The view illustrated in FIG. 3 is a view of the artificial hipjoint prosthesis in vivo in a resting, or not significantlyphysiologically flexed, position. The view illustrated in FIG. 3 is aview of the artificial hip joint prosthesis in vivo without thesurrounding skin, ligaments and other surrounding tissues depicted. Anembodiment of an artificial hip joint prosthesis such as illustrated inFIG. 3 can include an acetabular shell, although it is not visible inthe view depicted in FIG. 3.

FIG. 3 shows that the hip joint prosthesis 100 includes a visibleacetabular liner 175 positioned adjacent to the pelvis 160, forming abone-prosthesis interface 120. The acetabular liner 175 has a pluralityof fluid deflecting structures 140 attached. The fluid deflectingstructures 140 attached to the acetabular liner 175 are positionedaround the circumference of the acetabular liner 175 in a region of thenon-contact surface of the acetabular liner 175. In the view shown inFIG. 3, the hip joint prosthesis 100 is in a resting position and thesynovial fluid flow in the joint is not under significant pressure atany particular location. The fluid deflecting structures 140 attached tothe acetabular liner 175 are, therefore, positioned substantiallyperpendicularly relative to the surface of the acetabular liner 175facing the interior region of the joint 100. The fluid deflectingstructures 140 attached to the acetabular liner 175 are of a size, shapeand material fabrication to not impede motion of the joint 100,including being predicted to not come into contact with the femoral head182 or the femoral stem 187 during routine physiological activity.

FIG. 3 also depicts that the hip joint prosthesis 100 includes a femoralhead 182 and a femoral stem 187. A plurality of fluid deflectingstructures 145 are attached to the femoral stem 187. The plurality offluid deflecting structures 145 attached to the femoral stem 187 arepositioned around the circumference of the femoral stem 187 in a regionof the non-contact surface 135 of the femoral stem 187. As noted above,in the view shown in FIG. 3, the hip joint prosthesis 100 is in aresting position and the synovial fluid flow in the joint is not undersignificant pressure at any particular location. The fluid deflectingstructures 145 attached to the non-contact surface 135 of the femoralstem 187 are, therefore, positioned substantially perpendicularlyrelative to the surface of the femoral stem 187 facing the interiorregion of the joint 100. The fluid deflecting structures 145 attached tothe femoral stem 187 are of a size, shape and material fabrication tonot impede motion of the joint 100, including being predicted to notcome into contact with the femoral head 182 or the acetabular liner 175during routine physiological activity.

FIG. 4 depicts a hip joint prosthesis 100 in vivo during physiologicalmovement of the joint 100. The view illustrated in FIG. 4 is an externalview of the joint 100, similar to the view depicted in FIG. 3. As withthe viewpoint shown in FIG. 3, the mechanisms attached to the fluiddeflection structures 140 are not visible in FIG. 4. The artificial hipjoint prosthesis 100 depicted in FIG. 4 is depicted in vivo in a flexedor bent position, similar to the view depicted in cross-section in FIG.2. As illustrated in FIG. 4, the artificial hip joint prosthesis 100includes an acetabular liner 175, a femoral head 182 and a femoral stem187. FIG. 4 depicts the joint during or immediately after moving to aflexed position, which is expected to result in a transient increase insynovial fluid pressure at the bone-prosthesis interface regions putinto closer proximity during the joint repositioning. For example, FIG.4 illustrates that regions of the non-contact surface 130A of theacetabular liner 175 and a region of the non-contact surface 135A of thefemoral stem 187 are being placed in closer proximity due to the jointrepositioning (e.g. relative to the joint position illustrated in FIG.3). Correspondingly, FIG. 4 shows that regions of the non-contactsurface 130B of the acetabular liner 175 and a region of the non-contactsurface 135B of the femoral stem 187 are moved away from each other dueto the joint repositioning (e.g. relative to the joint positionillustrated in FIG. 3).

As also described above, for a transient period during and immediatelyafter the joint flexing or bending from the position illustrated in FIG.3 to the position illustrated in FIG. 4, there is an increase insynovial fluid pressure in the region between the non-contact surface130A of the acetabular liner 175 and a region of the non-contact surface135A of the femoral stem 187. This results in an increased synovialfluid flow across the joint, as illustrated by the dotted arrows acrossthe joint 100 in FIG. 4. The joint bending, and the associated localizedsynovial fluid pressure increase, results in pressure transferred asforce on the mechanisms attached to the fluid deflecting structures 140Aadjacent to the non-contact surface 130A of the acetabular liner 175.The joint bending, and the associated localized synovial fluid pressureincrease, also results in pressure transferred as force on themechanisms attached to the fluid deflecting structures 145A attached tothe non-contact surface 135A of the femoral stem 187. As shown in FIG.4, the fluid deflecting structures 140 B, 145B attached to thenon-contact surfaces 130B, 135B of the acetabular liner 175 and thefemoral stem 187 are not subject to increased synovial fluid pressure.The mechanisms attached to the fluid deflecting structures 140 B, 145Bnot under increased transient fluid pressure will, therefore, notrespond in the same manner as mechanisms attached to the fluiddeflecting structures 140A, 145A subject to the localized synovial fluidpressure increase associated with the joint bending.

FIG. 5 shows components of an artificial hip joint prosthesis ex-vivo.These components can be included in some embodiments of an artificialhip joint prosthesis, although not all embodiments will include all ofthe components depicted in FIG. 5. FIG. 5 depicts that the artificialhip joint prosthesis includes an acetabular shell 170. The acetabularshell 170 is configured to fit around an acetabular liner 175. Theacetabular liner 175 includes a non-contact surface 130. A plurality ofnon-actuated fluid deflecting structures 540 are attached to thenon-contact surface 130 of the acetabular liner 175. The artificial hipjoint prosthesis also includes a femoral head 182 configured to attachto a femoral stem 187 through routine means. The femoral head 182includes a non-contact surface 500. An actuated attachment 510 includesa surface configured to reversibly mate with the non-contact surface500. The actuated attachment 510 includes a plurality of actuated fluiddeflecting structures 520 attached to associated mechanisms 530. Themechanisms 530 are partially embedded within the structure of theactuated attachment 510. The actuated fluid deflecting structures 520are oriented to project outward from the non-contact surface 500 whenthe actuated attachment 510 is positioned in place adjacent to thenon-contact surface 500 of the femoral head 182. During use, theactuated attachment 510 is positioned adjacent to the non-contactsurface 500 of the femoral head 182. The plurality of actuated fluiddeflecting structures 520 attached to associated mechanisms 530 in theactuated attachment 510 are configured to move joint fluid in vivothrough action of the mechanisms 530. The femoral stem 187 includesnon-contact surface 135 with a plurality of attached fluid deflectingstructures 545 without associated mechanisms. The non-contact surfaces130, 500, 135 depicted in FIG. 5 are each predicted to not come intodirect contact with the adjacent surfaces of the artificial hip jointprosthesis during routine physiological use of the hip joint in vivo.

The fluid deflecting structures 520, 540, 545 shown in FIG. 5 aredepicted as substantially linear, or ciliated, structures. Thedimensions of substantially linear fluid deflecting structures 520, 540,545 such as height and diameter, would depend on the particularembodiment. In particular, the substantially linear fluid deflectingstructures 520, 540, 545 should be constructed of a size, shape andmaterial to not impede routine physiological use of the associated hipjoint in vivo while still providing fluid deflection during joint motion(e.g. as described relative to FIGS. 2 and 4, above). Similarly, thepositioning and number of the substantially linear fluid deflectingstructures 520, 540, 545 on the non-contact surfaces 130, 500, 135 willdepend on the specific embodiment. Factors to consider in the size,shape, positioning, number and material of the substantially linearfluid deflecting structures 520, 540, 545 on the non-contact surfaces130, 500, 135 in various embodiments include the total size of the hipjoint in vivo, the relative size of the hip joint components 170, 175,182, 187, and the expected fluid pressures within the hip joint in vivo.The relative number, size and position of the actuated fluid deflectingstructures 520 attached to mechanisms 530 to drive movement of theactuated fluid deflecting structures 520 relative to the number, sizeand position of non-actuated fluid deflecting structures 540, 545 willvary by embodiment. The non-actuated fluid deflecting structures 540,545 will act synergistically with the actuated fluid deflectingstructures 520 in vivo to deflect fluid within the joint. The position,spacing, size and shape of the non-actuated fluid deflecting structures540, 545 relative to the actuated fluid deflecting structures 520 on theartificial joint will determine the joint fluid flow and deflection inthe entirety of the joint in vivo.

FIG. 6 illustrates aspects of some embodiments of a femoral stem 187with attached fluid deflecting structures 145 on a non-contact surface135. The fluid deflecting structures 145 illustrated in FIG. 6 are notattached to mechanisms, and as such, they are “passive” or“non-actuated” fluid deflecting structures. As illustrated in FIG. 6, insome embodiments of a hip joint prosthesis, a non-contact surface 135includes a plurality of deflecting structures 145 attached to project atan angle from the non-contact surface 135. The plurality of deflectingstructures 145 are each attached to a band 600 at their terminal endclosest to the non-contact surface 135. The band 600 is configured tosecure each of the plurality of deflecting structures 145 in positionrelative to the non-contact surface 135. The band 600 illustrated inFIG. 5 is shown as a single, unified, smooth band, but in someembodiments the band 600 can include multiple components, grooves ortabs configured to stabilize the band 600 relative to the non-contactsurface 135. The band 600 is also stabilized relative to the non-contactsurface 135 through placement in a groove 610 of the non-contact surface135. The groove 610 of the non-contact surface 135 can have a single,substantially smooth surface, as shown in FIG. 6. In some embodiments,the groove 610 can include multiple channels or surfaces. For example,in some embodiments a groove 610 can include edge structures configuredto mate with corresponding tab structures of a band 600 to functionallystabilize the band 600 relative to the non-contact surface 135. Althougha band 600 and corresponding groove 610 are illustrated in FIG. 6relative to a femoral stem 187, some embodiments include a band 600 andcorresponding groove 610 on other components of an artificial joint,e.g. an acetabular cup. Although the band 600 and corresponding groove610 are shown in FIG. 6 relative to an artificial hip joint prosthesis,some embodiments include one or more bands 600 with attached fluiddeflecting structures 145 and corresponding grooves 610 on other typesof artificial joints, e.g. an artificial knee or shoulder.

FIG. 7A shows aspects of a femoral stem 187 including a plurality offluid deflecting structures 545 with attached mechanisms on anon-contact surface 135. A portion of the femoral stem 187 including thenon-contact surface 135 is shown in an enlarged view in FIG. 7B toillustrate aspects of a fluid deflecting structure 545 and attachedmechanism 730 relative to the non-contact surface 135. The non-contactsurface 135 includes a series of apertures 700, with each of theplurality of fluid deflecting structures 545 projecting through a singleaperture 700.

As illustrated and enlarged in FIG. 7B, a region of a fluid deflectingstructure 545 traverses through a single aperture 700. Each of theapertures 700 is positioned between the external non-contact surface 135and a cavity 710 in the femoral stem 187. The mechanism 730 attached tothe fluid deflecting structure 545 is positioned entirely within thecavity 710. Each cavity 710 is of a size and shape that is larger, inparticular wider, than the size of the adjacent aperture 700. Each ofthe fluid deflecting structures 545 includes a projection 720 at an endof the fluid deflecting structure 545 configured to fit within thecavity 710. The mechanism 730 is attached to the fluid deflectingstructure 545 at the projection 720. The size and the shape of theprojection 720 and associated mechanism 730 corresponds with the sizeand shape of the associated cavity 710 in a manner to stabilize thefluid deflecting structure 545 within the cavity 710 and associatedaperture 700. The size and the shape of the projection 720 andassociated mechanism 730 also corresponds with the size and shape of theassociated cavity 710 so that the mechanism 530 can operate within thecavity 710 to influence movement of the fluid deflection structure 545.The size and shape of the cavity 710 can, for example, position the endof the fluid deflecting structure 545 with the projection at aparticular angle relative to the non-contact surface 135. The size andshape of the cavity 710 can, for example, fix the end of the fluiddeflecting structure 545 with the projection relative to the non-contactsurface 135.

Although apertures 700, cavities 710 and corresponding projections 720from the fluid deflecting structures 545 with attached mechanisms 530are illustrated in FIG. 7 relative to a femoral stem 187, someembodiments include apertures 700, cavities 710 and correspondingprojections 720 associated with the fluid deflecting structures withattached mechanisms 530 associated with non-contact regions on othercomponents of an artificial joint, e.g. an acetabular cup or femoralhead component. Although the apertures 700, cavities 710 andcorresponding projections 720 from the fluid deflecting structures 545with attached mechanisms 530 are shown in FIGS. 7A and 7B relative to anartificial hip joint prosthesis, some embodiments include one or moreapertures 700, cavities 710 and corresponding projections 720 from thefluid deflecting structures 545 with attached mechanisms 530 on othertypes of artificial joints, e.g. an artificial knee or shoulder.

FIG. 8 illustrates aspects of an artificial knee joint 800 prosthesis invivo. The artificial knee joint 800 prosthesis illustrated in FIG. 8 isshown in a frontal view, with the surrounding skin, ligaments andtissues removed for clarity of presentation. The artificial knee joint800 shown in FIG. 8 includes components 830, 810 attached to both thefemur 813 and the tibia 823. A synovial membrane border 840 is shown asa dotted line to roughly define the edge of the synovial fluid region ofthe artificial knee joint 800. In some embodiments, an artificial kneejoint 800 prosthesis will be partial, i.e. not include all of thecomponents illustrated in FIG. 8.

FIG. 8 shows a femur 813 including an attached femoral component 810 ofan artificial knee joint 800 prosthesis. The femoral component 810includes a bone-facing surface, which is positioned relative to thefemur 813 in vivo to create a bone-prosthesis interface 817. The femoralcomponent 810 also includes a non-contact surface 862. The non-contactsurface 862 is a surface of the femoral component 810 that is predictedto not come into contact with other components of the artificial kneejoint 800, for example the tibial spacer 820 or the tibial component830, during normal physiological use of the artificial knee joint 800. Aplurality of fluid deflecting structures 852 are positioned adjacent tothe periphery of the non-contact surface 862 of the femoral component810.

The artificial knee joint 800 shown in FIG. 8 also includes a tibialcomponent 830 with a bone-facing surface attached to the tibia 823 invivo to form a bone-prosthesis interface 827. The tibial component 830is attached to a tibial spacer 820. In the embodiment illustrated inFIG. 8, the tibial spacer 820 includes a non-contact surface 864. Thenon-contact surface 864 is a surface of the tibial spacer 820 that ispredicted to not come into contact with other components of theartificial knee joint 800, for example the femoral component 810, duringnormal physiological use of the artificial knee joint 800. A pluralityof fluid deflecting structures 854 are positioned relative to theperiphery of the non-contact surface 864 of the tibial spacer 820.Although not shown in FIG. 8, some embodiments include one or more fluiddeflecting structures positioned relative to the periphery of anon-contact surface of the tibial component 830.

No mechanisms are illustrated in FIG. 8. However, embodiments includethose wherein some or all of the fluid deflecting structures 852, 854have attached mechanisms, the mechanisms configured to position thefluid deflecting structures 852, 854 to deflect joint fluid in vivo. Insome embodiments, the mechanisms are attached to the external surface ofthe non-contact regions and the associated fluid deflecting structures852, 854. In some embodiments, the mechanisms are positioned withincavities adjacent to the non-contact surfaces 862, 864 (e.g. asillustrated in FIG. 7B). The selection of which portion, or all, of thefluid deflection structures 852, 854 have attached mechanisms operableto move the fluid deflection structure to direct synovial fluid awayfrom the bone-prosthesis interface in vivo depends on the embodiment.Factors to consider include the size, shape, and expected physiologicaljoint pressures of the artificial knee joint. Similarly, the type ofmechanism selected in a given embodiment as operable to move an attachedfluid deflection structure depends on factors such as the size, mass,position and flexibility of the fluid deflection structure, as well asthe expected physiological fluid pressures during in vivo use of thejoint. Mechanisms attached to the external surface of the non-contactregion will operate with different parameters than those situated withina cavity adjacent to the surface. The fluid deflection structures withattached mechanisms will actively divert fluid flow within the joint.Some embodiments include fluid deflection structures without attachedmechanisms, the include fluid deflection structures without attachedmechanisms configured to assist the fluid deflection structures withattached mechanisms to deflect joint fluid away from the prosthesis-boneinterface in vivo.

The size, shape, and position of the fluid deflecting structures 852,854 are selected relative to the size and shape of the joint, as well asthe expected physiological fluid pressures during in vivo use of thejoint. The size, shape, and position of the fluid deflecting structures852, 854 are also selected relative to the requirements of any attachedmechanism, for example due to the position or mode of operation of themechanism. As shown in FIG. 8, in some embodiments the fluid deflectingstructures 852, 854 can be formed as substantially flat rectangularstructures with rounded edges. In some embodiments, the fluid deflectingstructures 852 can be formed as flanges or linear structures.

Some embodiments include fluid deflecting structures that are notattached to a mechanism, but are directly affixed to a component of theartificial knee joint. The fluid deflecting structures 852, 854 can beattached to the associated components, i.e. the femoral component 810,the tibial spacer 820 and the tibial component 830 with structuressuitable for a particular embodiment. For example, the fluid deflectingstructures 852, 854 can be attached to the associated components throughattachment to bands inserted into corresponding grooves in thecomponents (e.g. as shown in FIG. 6). For example, the fluid deflectingstructures 852, 854 can be attached to the associated components throughstabilization in cavities in the components (e.g. as shown in FIG. 7)with or without an associated mechanism to drive the motion of the fluiddeflection structure. For example, the fluid deflecting structures 852,854 can be attached to the associated components through adhesive, epoxyor glue. For example, the fluid deflecting structures 852, 854 can befabricated as part of the components, for example integral to acomponent fabricated from a plastic material such as polyethylene.

As FIG. 8 illustrates, in some embodiments an artificial knee joint 800prosthesis includes: a bone-facing surface of a knee joint prosthesis,the bone-facing surface configured to face a bone-prosthesis interface817, 827 in vivo; a non-contact surface 862, 864 of the knee jointprosthesis, the non-contact surface 862, 864 adjacent to the bone-facingsurface of the knee joint prosthesis; at least one fluid deflectionstructure 852, 854 positioned on the non-contact surface 862, 864, thefluid deflection structure 852, 854 positioned to deflect synovial fluidaway from the bone-prosthesis interface 817, 827 in vivo; and amechanism attached to the fluid deflection structure, the mechanismoperable to move the fluid deflection structure to direct synovial fluidaway from the bone-prosthesis interface in vivo. In some embodiments,the bone-facing surface of the artificial knee joint 800 prosthesisincludes one or more of: a bone-facing surface of a tibial spacercomponent of the knee joint prosthesis, a bone-facing surface of atibial component of the knee joint prosthesis, a bone-facing surface ofa femoral component of the knee joint prosthesis, or a bone-facingsurface of a patellar component of the knee joint prosthesis. In someembodiments, the non-contact surface 862, 864 of the knee jointprosthesis includes one or more of: a edge region 864 of a liner of atibial spacer component 820 of the knee joint prosthesis; a edge region862 of a tibial component 830 of the knee joint prosthesis; and a edgeregion of a patellar component of the knee joint prosthesis.

A fluid deflection structure associated with the non-contact surface ofan artificial knee joint can be configured in different shapes, asappropriate to the fluid deflection parameters of a specific embodiment.Some embodiments include at least one fluid deflection structurepositioned adjacent to the non-contact surface including at least oneflange structure positioned to extend from the non-contact surface. Insome embodiments, the at least one flange structure is positioned toextend from the non-contact surface at an angle varying substantiallybetween 10 degrees and 80 degrees of a plane established by the contactsurface and relative to the bone-facing surface of the knee jointprosthesis. In some embodiments, the at least one flange structure ispositioned to extend from the non-contact surface at an angle varyingsubstantially between 100 degrees and 170 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theknee joint prosthesis. Some embodiments include at least one flangestructure with a first end positioned adjacent to the non-contactsurface and a second end distal to the non-contact surface, wherein theflange structure is widest at the first end and narrowest at the secondend. Some embodiments include at least one flange structure with a firstend positioned adjacent to the non-contact surface and a second enddistal to the non-contact surface, wherein the flange structure tapersfrom a widest point at the first end to a narrow point at the secondend. Some embodiments include at least one flange structure with acurvilinear structure. Some embodiments include a plurality of flangestructures.

In some embodiments, one or more of the fluid deflection structuresassociated with a knee joint prosthesis include linear projections. Someembodiments include a plurality of linear projections. In someembodiments, the plurality of linear projections are positioned toextend from the non-contact surface at an angle varying substantiallybetween 10 degrees and 80 degrees of a plane established by the contactsurface and relative to the bone-facing surface of the knee jointprosthesis. In some embodiments, the plurality of linear projections arepositioned to extend from the non-contact surface at an angle varyingsubstantially between 100 degrees and 170 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theknee joint prosthesis.

Some embodiments include one or more fluid deflection structuresconfigured as substantially straight fluid deflection structures. Forexample, a substantially straight fluid deflection structure can beconfigured as a flat, substantially rectangular plane. Some embodimentsinclude one or more fluid deflection structures configured assubstantially curved fluid deflection structures. For example, asubstantially curved fluid deflection structure can be a curvilinear or“crescent” shaped structure.

In some embodiments, at least one fluid deflection structure positionedadjacent to the non-contact surface is configured to be substantiallyrigid at physiological conditions when the artificial joint is utilizedin vivo. For example, the fluid deflection structure can be fabricatedfrom a plastic material expected to be substantially rigid atphysiological temperatures and joint fluid pressures. In someembodiments, at least one fluid deflection structure positioned adjacentto the non-contact surface is configured to be flexible at physiologicalconditions when the artificial joint is utilized in vivo. For example,the fluid deflection structure can be fabricated from a plastic materialexpected to be substantially flexible at physiological temperatures andjoint fluid pressures. Fluid deflection structures can be fabricated,for example, from plastic or metal components as suitable forimplantation and use in vivo.

The selection of the size and shape of the fluid deflection structuresutilized in a specific embodiment is particular to the expectedparameters of that embodiment. For example, in some embodiments the atleast one fluid deflection structure positioned adjacent to thenon-contact surface is configured to flex to a degree sufficient topermit a larger synovial fluid flow rate away from the bone-prosthesisinterface during periods of increased synovial fluid pressure in theregion of the non-contact surface when the artificial joint is utilizedin vivo at physiological conditions, and to permit a smaller synovialfluid flow rate away from the bone-prosthesis interface during periodsof reduced synovial fluid pressure when the artificial joint is utilizedin vivo at physiological conditions. For example, in some embodimentsthe at least one fluid deflection structure positioned adjacent to thenon-contact surface is configured to flex to a degree sufficient topermit an increased synovial fluid flow rate away from thebone-prosthesis interface in response to increased fluid pressure in aregion adjacent to the bone-prosthesis interface.

The mechanism attached to a fluid deflection structure will similarlyvary depending on the specific embodiment. Factors to consider in theselection of a mechanism include the size, shape, durability, mass, costand force operable on an attached fluid deflection structure. Somemechanisms attached to a fluid deflection structure are configured to beattached to a non-contact surface of an artificial knee joint prosthesiscomponent. Some mechanisms attached to a fluid deflection structure areconfigured to be substantially enclosed within the artificial knee jointprosthesis. For example, the mechanism and attached fluid deflectionstructure can be positioned adjacent to the non-contact surface of theknee prosthesis, such as with epoxy, glue, or other adhesives. Forexample, the mechanism with the attached fluid deflection structure canbe configured to mate with a corresponding surface on the non-contactregion of the knee prosthesis. In some embodiments, the mechanismattached to the fluid deflection structure is substantially enclosedwithin the artificial knee joint prosthesis. For example, the mechanismattached to the fluid deflection structure can be substantially enclosedwithin a cavity or groove in the non-contact region of the knee jointprosthesis. For example, the mechanism attached to the fluid deflectionstructure can be substantially enclosed within an extension of the kneejoint prosthesis configured to attach the mechanism. The mechanism canbe a micromachine, for example one in the size range of 100 nanometers(nm) to 100 micrometers (μm) in diameter. The mechanism can be a MEMSdevice, for example with a size range of 20 μm to 1 millimeter (mm) indiameter.

The mechanism attached to the fluid deflection structure and operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone-knee joint prosthesis interface in vivo can be of a variety oftypes, depending on the embodiment. Factors to be used in the selectionof a mechanism include: the force on the fluid deflection structuredesired to deflect the fluid; the size, shape and flexibility of thefluid deflection structures; the size of the mechanism; the cost of themechanism; and the expected duration of use of the artificial knee jointprosthesis in vivo. In some embodiments, the mechanism attached to thefluid deflection structure includes an actuator attached to the fluiddeflection structure and configured to move the fluid deflectionstructure. For example, an actuator can include a hydraulic piston,which can be positioned within a cavity formed in the knee prosthesis.In embodiments wherein the mechanism attached to the fluid deflectionstructure includes an actuator with a hydraulic piston, force from fluidflow against the fluid deflection structure can be transmitted to thepiston, with a resulting reverse force transmitted back to the fluiddeflection structure to drive movement of the fluid deflectionstructure. Some embodiments include a battery configured to provideenergy to the actuator. For example, the actuator can include anelectric motor which is connected to an attached battery.

In some embodiments, the mechanism attached to the fluid deflectionstructure includes piezoelectric material, the piezoelectric materialconfigured to drive movement of the at least one fluid deflectionstructure. For example, in some embodiments a piezoelectric materialattached to a fluid deflection structure can be configured to generateelectrical charge from the pressure force on the fluid deflectionstructure, and then store the electrical charge in an attached battery.The stored charge in the battery can then be utilized to drive the samefluid deflection structure, or a second fluid deflection structure, withan attached electric motor. Instead or in addition, the stored charge inthe battery can be utilized to drive the same fluid deflection structurethrough re-introduction of the electrical charge to the piezoelectricmaterial, with the resulting reverse piezoelectric effect resulting inpressure force on the fluid deflection structure due to the expansion ofthe piezoelectric material.

In some embodiments, the mechanism attached to the fluid deflectionstructure and operable to move the fluid deflection structure to directsynovial fluid away from the bone-knee joint prosthesis interface invivo includes at least one magnetic actuator, the magnetic actuatorconfigured to drive movement of the at least one fluid deflectionstructure.

Some embodiments include: an aperture in the non-contact surface of theartificial knee joint prosthesis; a substantially round cavity in theartificial knee joint prosthesis adjacent to the aperture; the mechanismincluding a substantially round element of a size and shape tocorrespond to the substantially round cavity, the substantially roundelement positioned within the substantially round cavity and configuredto move within the substantially round cavity; and the at least onefluid deflection structure attached to the substantially round elementand projecting through the aperture. For example, the mechanism can beconfigured with a substantially round external shape, of a size andshape to reversibly mate with the internal surface of the substantiallyround cavity in the artificial knee joint prosthesis. A mechanism with asubstantially round external shape within a substantially round cavitycan rotate in the cavity, with the resulting movement of a fluiddeflection structure attached to the mechanism and projecting through anaperture between the cavity and the external surface of the kneeprosthesis. The mechanism can utilize the force transmitted by the jointfluid through the fluid deflection structure, such as through theoperation of a piezoelectric material or hydraulic piston, to drivefurther movement of the attached fluid deflection structure. Themechanism can be configured as a ball-like structure to rotate withinthe cavity in multiple directions. The mechanism can be configured as acylindrical structure, with a corresponding cylindrical cavity, torotate specifically along the axis formed by the radius of thecylindrical structure.

Some embodiments of an artificial knee joint prosthesis include: atleast one first magnet attached to the artificial knee joint prosthesis;and at least one second magnet attached to the fluid deflectionstructure, wherein the mechanism attached to the fluid deflectionstructure is configured to move in accord with a magnetic fieldestablished by the at least one first magnet. Some embodiments of anartificial joint prosthesis include: at least one first magnet attachedto the artificial knee joint prosthesis; and at least one second magnetattached to the fluid deflection structure, wherein the mechanismattached to the fluid deflection structure is configured to allow the atleast one second magnet to move the fluid deflection structure in accordwith a magnetic field established by the at least one first magnet. Themagnets can be configured as a mechanism attached to the fluiddeflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from the bone-kneejoint prosthesis interface in vivo. The magnets can be configured toassist a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure.

Some embodiments of an artificial knee joint prosthesis include at leasttwo components, each of which include at least one fluid deflectionstructure, and each of which include the mechanism attached to the fluiddeflection structure, each of the mechanisms operable to move each ofthe fluid deflection structures to direct synovial fluid away from thebone-knee joint prosthesis interface in vivo. For example, an artificialknee prosthesis can include a femoral component and a tibial component,each of which include at least one fluid deflection structure with anattached mechanism, each of the mechanisms operable to move each of thefluid deflection structures to direct synovial fluid away from thebone-prosthesis interface in vivo during physiological use of theartificial knee joint. Some embodiments of an artificial knee jointprosthesis include: at least one femoral component, wherein the femoralcomponent includes at least one fluid deflection structure positionedadjacent to the non-contact surface and at least one mechanism attachedto the at least one fluid deflection structure; and at least one tibialcomponent, wherein the tibial component includes at least one fluiddeflection structure positioned adjacent to the non-contact surface andat least one mechanism attached to the at least one fluid deflectionstructure.

FIG. 9 shows a view of an embodiment similar to that shown in FIG. 8,from a side-facing view relative to the individual. The embodimentillustrated in FIG. 9 is shown in a side view, with the surroundingskin, ligaments and tissues removed for clarity of presentation. Theartificial knee joint 800 shown in FIG. 9 includes artificial jointcomponents 830, 810 attached to both the femur 813 and the tibia 823. Apatella is not depicted, although some embodiments include an artificialpatella that is part of the artificial knee joint 800.

As shown in FIG. 9, the femur 813 has an attached femoral component 810.The femoral component 810 includes a region with a non-contact surface862. Associated with the non-contact surface 862 of the femoralcomponent 810 are a series of fluid deflecting structures 852. The fluiddeflecting structures 852 are configured to reduce synovial fluid flowat the bone-implant interface 817 in vivo. The fluid deflectingstructures 852 are configured to reduce synovial fluid pressure at thebone-implant interface 817 in vivo during physiological use of the kneejoint. Although not illustrated in FIG. 9, some or all of the fluiddeflecting structures 852 are attached to a mechanism operable to movethe fluid deflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo. Depending on the embodiment, some ofthe fluid deflecting structures 852 are attached directly to thenon-contact surface 862 without attached mechanisms.

FIG. 9 also shows that a tibial component 830 and a tibial spacer 820 ofthe artificial knee joint 800 are attached to the tibia 823. The tibialcomponent 830 has a bone-facing surface configured to form abone-implant interface 827 in vivo. The tibial spacer 820 includes aregion with a non-contact surface 864. Attached to the non-contactsurface 864 of the tibial spacer 820 are a series of fluid deflectingstructures 854. The fluid deflecting structures 854 are configured toreduce synovial fluid flow at the bone-implant interface 827 in vivo.The fluid deflecting structures 854 are configured to reduce synovialfluid pressure at the bone-implant interface 827 in vivo duringphysiological use of the knee joint. Although not illustrated in FIG. 9,some or all of the fluid deflecting structures 854 are attached to amechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.Depending on the embodiment, some of the fluid deflecting structures 854are attached directly to the non-contact surface 864 without attachedmechanisms.

The exact placement, size, shape and positioning of the fluid deflectingstructures 852, 854 attached to an artificial knee joint 800 prosthesiswill vary depending on the embodiment. For example, the size, shape,positioning, placement and fabrication of the fluid deflectingstructures 852, 854 will vary depending on the expected synovial fluidflow during physiological movement in vivo and the size and shape of theartificial knee joint 800. The particular fluid deflecting structures852, 854 for an embodiment will be configured to mitigate synovial fluidflow rates at the bone-implant interfaces 817, 827 in vivo, includingwith their attached mechanisms operable to move the fluid deflectionstructure to direct synovial fluid away from the bone-prosthesisinterface in vivo. The particular fluid deflecting structures 852, 854for an embodiment and any attached mechanisms will be configured toreduce transient synovial fluid pressure at the bone-implant interfaces817, 827 during physiological use in vivo.

As shown in situ in FIGS. 8 and 9, a knee joint prosthesis includes: atleast one bone-facing surface of a knee joint prosthesis, thebone-facing surface configured to face a bone-prosthesis interface 817,827 in vivo; a non-contact surface 862, 864 of the knee jointprosthesis, the non-contact surface 862, 864 adjacent to the bone-facingsurface 817, 827 of the knee joint prosthesis; at least one fluiddeflection structure 852, 854 positioned on the non-contact surface 862,864, the fluid deflection structure 852, 854 positioned to deflectsynovial fluid away from the bone-prosthesis interface 817, 827 in vivo;and a mechanism operable to move the fluid deflection structure todirect synovial fluid away from the bone-prosthesis interface in vivo.In some embodiments, the bone-facing surface of the knee jointprosthesis includes a bone-facing surface of a tibial spacer 820component of the knee joint prosthesis. In some embodiments, thebone-facing surface of the knee joint prosthesis includes a bone-facingsurface of a tibial component 830 of the knee joint prosthesis. In someembodiments, the bone-facing surface of the knee joint prosthesisincludes bone-facing surface of a femoral component 810 of the kneejoint prosthesis. In some embodiments, the bone-facing surface of theknee joint prosthesis includes bone-facing surface of a patellarcomponent of the knee joint prosthesis.

A knee joint prosthesis includes at least one non-contact surface 862,864. The non-contact surface 862, 864 is a surface of the knee jointprosthesis in a region that is not expected to come in contact withanother surface of a different region of the knee joint prosthesisduring normal physiological movement of the knee joint in vivo. Some ofthe non-contact surfaces 862, 864 of a knee joint prosthesis areattached to at least one fluid deflection structure 852, 854. A fluiddeflection structure can be of a variety of sizes and shapes, configuredto mitigate synovial fluid flow rate and fluid pressure at thebone-prosthesis interface during physiological use of the prosthesis invivo. A fluid deflection structure is configured to mitigate synovialfluid flow rate and fluid pressure at the bone-prosthesis interfacewithout impeding joint movement. Some or all of the fluid deflectionstructures of a knee joint prosthesis are attached to a mechanism, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.

Some embodiments include a shoulder joint prosthesis including: abone-facing surface of a shoulder joint prosthesis, the bone-facingsurface configured to face a bone-prosthesis interface in vivo; anon-contact surface of the shoulder joint prosthesis, the non-contactsurface adjacent to the bone-facing surface of the shoulder jointprosthesis; at least one fluid deflection structure positioned adjacentto the non-contact surface, the fluid deflection structure positioned todeflect synovial fluid away from the bone-prosthesis interface in vivo;and a mechanism attached to the fluid deflection structure, themechanism operable to move the fluid deflection structure to directsynovial fluid away from the bone-prosthesis interface in vivo.

For example, FIG. 10 illustrates a shoulder joint prosthesis 1000 invivo, including a humerus bone 1010 with an attached humerus spacer 1013and humerus cap 1017 of the prosthesis. There is a humerusbone-prosthesis interface 1043 between the humerus bone 1010 and thehumerus spacer 1013. The shoulder joint prosthesis 1000 shown in FIG. 10also includes a glenoid component 1023 attached to a glenoid cavity 1020of the scapula bone. A synovial membrane 1030 is illustrated to roughlydefine the area within the joint that will contain synovial fluid invivo. The embodiment illustrated in FIG. 10 is a conventional shoulderjoint prosthesis, however some embodiments include a shoulder jointprosthesis that is a reverse shoulder joint prosthesis.

Each of the individual components of the shoulder joint prosthesis 1000shown in FIG. 10 includes a bone-facing surface. The bone-facingsurfaces of the components are not visible in FIG. 10 as the shoulderjoint prosthesis 1000 is illustrated in vivo, with the bone-facingsurfaces obscured by the bone-prosthesis interfaces and theprosthesis-prosthesis interfaces. There is a scapula bone-prosthesisinterface 1053 between the glenoid component 1023 of the prosthesis andthe glenoid cavity 1020 of the scapula bone, with the region of theglenoid component 1023 facing the glenoid cavity 1020 of the scapulabone forming a bone-facing surface. There is a bone-prosthesis interface1043 between the humerus 1010 and the humerus spacer 1013, with theregion of the humerus spacer 1013 facing the humerus 1010 forming abone-facing surface. There is a prosthesis-prosthesis interface betweenthe humerus cap 1017 and the humerus spacer 1013, with a region of thehumerus cap 1017 forming a bone-facing surface. The bone-facing surfaceof the humerus cap 1017 does not contact the bone, however it faces thehumerus 1010 and thus forms a bone-facing surface. In some embodiments,the bone-facing surface of the shoulder joint prosthesis includes abone-facing surface of a liner of a glenoid component of the shoulderjoint prosthesis. In some embodiments, the bone-facing surface of theshoulder joint prosthesis includes a bone-facing surface of a glenoidfixation component of the shoulder joint prosthesis. In someembodiments, the bone-facing surface of the shoulder joint prosthesisincludes a bone-facing surface of a humeral head component of theshoulder joint prosthesis. In some embodiments, the bone-facing surfaceof the shoulder joint prosthesis includes a bone-facing surface of astem of a humeral component of the shoulder joint prosthesis.

A non-contact surface 1040, 1050 of a shoulder joint prosthesis 1000 isa surface of a region of the shoulder joint prosthesis 1000 that ispredicted to not come into contact with another component of theshoulder joint during normal physiological movement of the joint. Asshown in FIG. 10, the humerus spacer 1013 has a non-contact surface 1040around the edge surrounding the bone-prosthesis interface 1043. Someembodiments of a shoulder joint prosthesis include a non-contact surfacethat is a edge region of a humeral head component of the shoulder jointprosthesis. Some embodiments of a shoulder joint prosthesis include anon-contact surface that is a edge region of a stem of a humeralcomponent of the shoulder joint prosthesis. The glenoid component 1023also has a non-contact surface 1050 surrounding the edge of the glenoidcomponent 1023 adjacent to the scapula bone-prosthesis interface 1053.Some embodiments of a shoulder joint prosthesis include a non-contactsurface that is a edge region of a glenoid component of the shoulderjoint prosthesis. Some embodiments of a shoulder joint prosthesisinclude a non-contact surface that is a edge region of a glenoidfixation component of the shoulder joint prosthesis.

The shoulder joint prosthesis 1000 shown in FIG. 10 includes a pluralityof fluid deflecting structures 1047 associated with the non-contactsurface 1040 of the humerus spacer 1013. The shoulder joint prosthesis1000 shown in FIG. 10 also includes a plurality of fluid deflectingstructures 1057 associated with the non-contact surface 1050 surroundingthe edge of the glenoid component 1023. A fluid deflection structure1047, 1057 of a shoulder joint prosthesis 1000 is a structure associatedwith a non-contact surface 1040, 1050 and configured to mitigate fluidflow and reduce transient fluid pressure at a bone-prosthesis interface1043, 1053 during physiological use of the shoulder joint in vivo. Afluid deflecting structure can be associated with a non-contact surfaceof a shoulder joint prosthesis by a variety of means, depending on theembodiment. For example, a fluid deflecting structure can be attached toa mechanism, the mechanism attached to the non-contact surface. Forexample, a fluid deflecting structure can include an end regionconfigured to stabilize the fluid deflecting structure within a cavityin a prosthesis component, with an attached mechanism within the cavity(see, e.g. FIG. 7). For example, a passive, or non-actuated, fluiddeflecting structure without an attached mechanism can be attached to anon-contact surface directly. For example, a fluid deflecting structurecan be attached to a non-contact surface of a shoulder joint prosthesisby glue, adhesive or epoxy. For example, a fluid deflecting structurecan be attached to a band, which is then stabilized in a groove in anon-contact surface of a shoulder joint prosthesis (see, e.g. FIG. 6).

In some embodiments, the at least one fluid deflection structurepositioned on the non-contact surface includes at least one flangestructure positioned to extend from the non-contact surface. Forexample, in some embodiments the at least one flange structure ispositioned to extend from the non-contact surface at an anglesubstantially between 10 degrees and 80 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theshoulder joint prosthesis. Some embodiments include at least one flangestructure positioned to extend from the non-contact surface at an anglesubstantially between 100 degrees and 170 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theshoulder joint prosthesis. Some embodiments include at least one flangestructure positioned to extend from the non-contact surface at asubstantially right angle from a plane established by the contactsurface and relative to the bone-facing surface of the shoulder jointprosthesis. A flange structure can include at least one flange structurewith a first end connected to the non-contact surface and a second enddistal to the non-contact surface, wherein the flange structure iswidest at the first end and narrowest at the second end. A flangestructure can include at least one flange structure with a first endconnected to the non-contact surface and a second end distal to thenon-contact surface, wherein the flange structure tapers from a widestpoint at the first end to a narrow point at the second end. A flangestructure can include at least one flange structure with a curvilinearstructure. A flange structure can include at least one flange structurewith a substantially straight structure.

As shown in FIG. 10, in some embodiments a shoulder joint prosthesis1000 includes at least one fluid deflection structure with a first endassociated with the non-contact surface and a second end distal to thenon-contact surface. Also as shown in FIG. 10, some embodiments includea plurality of fluid deflection structures associated with one or morenon-contact surfaces. For example, some embodiments include at least onescapular component, wherein the scapular component includes at least onefluid deflection structure positioned on the non-contact surface, and atleast one humeral component, wherein the humeral component includes atleast one fluid deflection structure positioned on the non-contactsurface. Some embodiments include a single fluid deflection structure,for example a fluid deflection structure encircling the edge of anon-contact surface.

In some embodiments, a shoulder joint prosthesis 1000 includes at leastone fluid deflection structure including a plurality of linearprojections. For example, the plurality of linear projections can beshaped as rods or cilia, for example as hair-like projections. See, e.g.FIG. 5. Fluid deflection structures configured as linear projections canbe positioned to extend from the non-contact surface at an anglesubstantially between 10 degrees and 80 degrees of a plane establishedby the contact surface and relative to the bone-facing surface of theshoulder joint prosthesis. Fluid deflection structures configured aslinear projections can be positioned to extend from the non-contactsurface at an angle substantially between 100 degrees and 170 degrees ofa plane established by the contact surface and relative to thebone-facing surface of the shoulder joint prosthesis. Fluid deflectionstructures configured as linear projections can be positioned to extendfrom the non-contact surface at an substantially right angle from aplane established by the contact surface and relative to the bone-facingsurface of the shoulder joint prosthesis.

Depending on the embodiment, a fluid deflection structure associatedwith a non-contact surface of a shoulder joint prosthesis can beconfigured in a variety of forms to mitigate synovial fluid flow andpressure at the bone-prosthesis interface. The specific size, shape andconfiguration of a fluid deflection structure depends on the embodiment,including the size, shape, and expected physiological stresses on ashoulder joint during routine use. Some embodiments include at least onefluid deflection structure positioned on the non-contact surface whereinthe at least one fluid deflection structure is configured as asubstantially straight fluid deflection structure. Some embodimentsinclude at least one fluid deflection structure positioned on thenon-contact surface wherein the at least one fluid deflection structureis configured as a substantially curved fluid deflection structure. Insome embodiments, at least one fluid deflection structure positioned ona non-contact surface of an artificial shoulder joint prosthesis isconfigured to be flexible at physiological conditions when theartificial joint is utilized in vivo. In some embodiments, at least onefluid deflection structure positioned on a non-contact surface of anartificial shoulder joint prosthesis is configured to flex to a degreesufficient to permit a larger synovial fluid flow rate away from thebone-prosthesis interface during periods of increased synovial fluidpressure in the region of the non-contact surface when the artificialjoint is utilized in vivo at physiological conditions, and to permit asmaller synovial fluid flow rate away from the bone-prosthesis interfaceduring periods of reduced synovial fluid pressure when the artificialjoint is utilized in vivo at physiological conditions. In someembodiments, at least one fluid deflection structure positioned on anon-contact surface of an artificial shoulder joint is configured toflex to a degree sufficient to permit an increased synovial fluid flowrate away from the bone-prosthesis interface in response to increasedfluid pressure in a region adjacent to the bone-prosthesis interface.

The mechanism attached to a fluid deflection structure of a shoulderjoint prosthesis will similarly vary depending on the specificembodiment. Factors to consider in the selection of a mechanism includethe size, shape, durability, mass, cost and force operable on anattached fluid deflection structure. Some mechanisms attached to a fluiddeflection structure are configured to be attached to a non-contactsurface of an artificial shoulder joint prosthesis component. Somemechanisms attached to a fluid deflection structure are configured to besubstantially enclosed within the artificial shoulder joint prosthesis.For example, the mechanism and attached fluid deflection structure canbe positioned adjacent to the non-contact surface of the shoulderprosthesis, such as with epoxy, glue, or other adhesives. For example,the mechanism with the attached fluid deflection structure can beconfigured to mate with a corresponding surface on the non-contactregion of the shoulder prosthesis. In some embodiments, the mechanismattached to the fluid deflection structure is substantially enclosedwithin the artificial shoulder joint prosthesis. For example, themechanism attached to the fluid deflection structure can besubstantially enclosed within a cavity or groove in the non-contactregion of the shoulder joint prosthesis. For example, the mechanismattached to the fluid deflection structure can be substantially enclosedwithin an extension of the shoulder joint prosthesis configured toattach the mechanism. The mechanism can be a micromachine, for exampleone in the size range of 100 nanometers (nm) to 100 micrometers (μm) indiameter. The mechanism can be a MEMS device, for example with a sizerange of 20 μm to 1 millimeter (mm) in diameter.

The mechanism attached to the fluid deflection structure and operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone—shoulder joint prosthesis interface in vivo can be of a varietyof types, depending on the embodiment. Factors to be used in theselection of a mechanism include: the force on the fluid deflectionstructure desired to deflect the fluid; the size, shape and flexibilityof the fluid deflection structures; the size of the mechanism; the costof the mechanism; and the expected duration of use of the artificialshoulder joint prosthesis in vivo. In some embodiments, the mechanismattached to the fluid deflection structure includes an actuator attachedto the fluid deflection structure and configured to move the fluiddeflection structure. For example, an actuator can include a hydraulicpiston, which can be positioned within a cavity formed in the shoulderprosthesis. In embodiments wherein the mechanism attached to the fluiddeflection structure includes an actuator with a hydraulic piston, forcefrom fluid flow against the fluid deflection structure can betransmitted to the piston, with a resulting reverse force transmittedback to the fluid deflection structure to drive movement of the fluiddeflection structure. Some embodiments include a battery configured toprovide energy to the actuator. For example, the actuator can include anelectric motor which is connected to an attached battery.

In some embodiments, the mechanism attached to the fluid deflectionstructure includes piezoelectric material, the piezoelectric materialconfigured to drive movement of the at least one fluid deflectionstructure. For example, in some embodiments a piezoelectric materialattached to a fluid deflection structure can be configured to generateelectrical charge from the pressure force on the fluid deflectionstructure, and then store the electrical charge in an attached battery.The stored charge in the battery can then be utilized to drive the samefluid deflection structure, or a second fluid deflection structure, withan attached electric motor. Instead or in addition, the stored charge inthe battery can be utilized to drive the same fluid deflection structurethrough re-introduction of the electrical charge to the piezoelectricmaterial, with the resulting reverse piezoelectric effect resulting inpressure force on the fluid deflection structure due to the expansion ofthe piezoelectric material.

In some embodiments, the mechanism attached to the fluid deflectionstructure and operable to move the fluid deflection structure to directsynovial fluid away from the bone—shoulder joint prosthesis interface invivo includes at least one magnetic actuator, the magnetic actuatorconfigured to drive movement of the at least one fluid deflectionstructure.

Some embodiments include: an aperture in the non-contact surface of theartificial shoulder joint prosthesis; a substantially round cavity inthe artificial shoulder joint prosthesis adjacent to the aperture; themechanism including a substantially round element of a size and shape tocorrespond to the substantially round cavity, the substantially roundelement positioned within the substantially round cavity and configuredto move within the substantially round cavity; and the at least onefluid deflection structure attached to the substantially round elementand projecting through the aperture. For example, the mechanism can beconfigured with a substantially round external shape, of a size andshape to reversibly mate with the internal surface of the substantiallyround cavity in the artificial shoulder joint prosthesis. A mechanismwith a substantially round external shape within a substantially roundcavity can rotate in the cavity, with the resulting movement of a fluiddeflection structure attached to the mechanism and projecting through anaperture between the cavity and the external surface of the shoulderprosthesis. The mechanism can utilize the force transmitted by the jointfluid through the fluid deflection structure, such as through theoperation of a piezoelectric material or hydraulic piston, to drivefurther movement of the attached fluid deflection structure. Themechanism can be configured as a ball-like structure to rotate withinthe cavity in multiple directions. The mechanism can be configured as acylindrical structure, with a corresponding cylindrical cavity, torotate specifically along the axis formed by the radius of thecylindrical structure.

Some embodiments of an artificial shoulder joint prosthesis include: atleast one first magnet attached to the artificial shoulder jointprosthesis; and at least one second magnet attached to the fluiddeflection structure, wherein the mechanism attached to the fluiddeflection structure is configured to move in accord with a magneticfield established by the at least one first magnet. Some embodiments ofan artificial shoulder joint prosthesis include: at least one firstmagnet attached to the artificial shoulder joint prosthesis; and atleast one second magnet attached to the fluid deflection structure,wherein the mechanism attached to the fluid deflection structure isconfigured to allow the at least one second magnet to move the fluiddeflection structure in accord with a magnetic field established by theat least one first magnet. The magnets can be configured as a mechanismattached to the fluid deflection structure, the mechanism operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone—shoulder joint prosthesis interface in vivo. The magnets can beconfigured to assist a mechanism attached to the fluid deflectionstructure, the mechanism operable to move the fluid deflectionstructure.

Some embodiments of an artificial shoulder joint prosthesis include atleast two components, each of which include at least one fluiddeflection structure, and each of which include the mechanism attachedto the fluid deflection structure, each of the mechanisms operable tomove each of the fluid deflection structures to direct synovial fluidaway from the bone—shoulder joint prosthesis interface in vivo. Forexample, an artificial shoulder prosthesis can include a glenoidcomponent and a humeral component, each of which include at least onefluid deflection structure with an attached mechanism, each of themechanisms operable to move each of the fluid deflection structures todirect synovial fluid away from the bone-prosthesis interface in vivoduring physiological use of the artificial shoulder joint. Someembodiments of an artificial shoulder joint prosthesis include: at leastone genoid component, wherein the glenoid component includes at leastone fluid deflection structure positioned adjacent to the non-contactsurface and at least one mechanism attached to the at least one fluiddeflection structure; and at least one humeral component, wherein thehumeral component includes at least one fluid deflection structurepositioned adjacent to the non-contact surface and at least onemechanism attached to the at least one fluid deflection structure.

One skilled in the art will recognize that the herein describedcomponents (e.g., operations), devices, objects, and the discussionaccompanying them are used as examples for the sake of conceptualclarity and that various configuration modifications are contemplated.Consequently, as used herein, the specific exemplars set forth and theaccompanying discussion are intended to be representative of their moregeneral classes. In general, use of any specific exemplar is intended tobe representative of its class, and the non-inclusion of specificcomponents, devices, and objects should not be taken limiting.

With respect to the use of substantially any plural and/or singularterms herein, those having skill in the art can translate from theplural to the singular and/or from the singular to the plural as isappropriate to the context and/or application. The varioussingular/plural permutations are not expressly set forth herein for sakeof clarity.

The herein described subject matter sometimes illustrates differentcomponents contained within, or connected with, different othercomponents. It is to be understood that such depicted architectures aremerely exemplary, and that in fact many other architectures may beimplemented which achieve the same functionality. In a conceptual sense,any arrangement of components to achieve the same functionality iseffectively “associated” such that the desired functionality isachieved. Hence, any two components herein combined to achieve aparticular functionality can be seen as “associated with” each othersuch that the desired functionality is achieved, irrespective ofarchitectures or intermedial components. Likewise, any two components soassociated can also be viewed as being “operably connected”, or“operably coupled,” to each other to achieve the desired functionality,and any two components capable of being so associated can also be viewedas being “operably couplable,” to each other to achieve the desiredfunctionality. Specific examples of operably couplable include but arenot limited to physically mateable and/or physically interactingcomponents. In some instances, one or more components may be similarlyreferred to herein as “configured to,” “configured by,” “configurableto,” “operable/operative to,” “adapted/adaptable,” “able to,”“conformable/conformed to,” etc.

This application may make reference to one or more trademarks, e.g., aword, letter, symbol, or device adopted by one manufacturer or merchantand used to identify and/or distinguish his or her product from those ofothers. Trademark names used herein are set forth in such language thatmakes clear their identity, that distinguishes them from commondescriptive nouns, that have fixed and definite meanings, or, in many ifnot all cases, are accompanied by other specific identification usingterms not covered by trademark. In addition, trademark names used hereinhave meanings that are well-known and defined in the literature, or donot refer to products or compounds for which knowledge of one or moretrade secrets is required in order to divine their meaning. Alltrademarks referenced in this application are the property of theirrespective owners, and the appearance of one or more trademarks in thisapplication does not diminish or otherwise adversely affect the validityof the one or more trademarks. All trademarks, registered orunregistered, that appear in this application are assumed to include aproper trademark symbol, e.g., the circle R or bracketed capitalization(e.g., [trademark name]), even when such trademark symbol does notexplicitly appear next to the trademark. To the extent a trademark isused in a descriptive manner to refer to a product or process, thattrademark should be interpreted to represent the corresponding productor process as of the date of the filing of this patent application.

EXAMPLES Example 1 An Artificial Hip Joint Including Fluid DeflectorStructures Configured to Divert and Diffuse Synovial Fluid Flow

A hip joint prosthesis is fabricated with fluid deflector structures onselect non-contact surfaces of the device. The fluid deflectorstructures are designed to divert joint fluids away from interfacesbetween the artificial device and the patient's bone, and to reduce thevelocity of fluid flow in the artificial joint, thereby reducing thelikelihood of aseptic loosening of the prosthetic implant. The fluiddeflector structures are also configured to minimally impede jointfunction and mobility in vivo. The hip joint prosthesis includes afemoral component which includes a head (or ball), a neck attached tothe head, and a stem which is configured to be implanted in themedullary canal of the femur. See, e.g. FIG. 1. The hip joint prosthesisalso includes an acetabular component which forms a socket. The socketof the acetabular component includes an outer and inner cup, with theouter cup configured to be attached to pelvic bone and the inner cupconfigured to bear the head of the femoral component. See, e.g. FIGS. 1and 2.

The neck and stem of the femoral component are made from titanium (seee.g., U.S. Pat. No. 6,761,741, “Prosthetic Joint,” to Iesaka and USPatent Application No. 2003/0229398 “Prosthetic Joint,” to Iesaka, whichare each incorporated herein by reference). The femoral component of theartificial joint is fabricated by processes of investment casting andmilling. For example, a solid model comprised of a thermally labilematerial (e.g., wax) is made by injection molding and then a ceramicshell is created by coating the solid wax model. The ceramic shell isrecovered after melting the solid model and used as a mold to cast thefemoral component of the prosthesis. See e.g., U.S. Pat. No. 5,665,118,“Bone Prostheses with Direct Cast Macrotextured Surface Regions andMethod for Manufacturing the Same,” to LaSalle et al., which isincorporated herein by reference.

At the base of the femoral component neck and the top of the femoralcomponent stem, a row of fluid deflector structures (see e.g. FIG. 5)are attached. The fluid deflector structures are positioned and shapedin a manner predicted to deflect synovial fluids away from the interfacebetween the femur and the implanted stem, and to diffuse the fluidpressure at the interface, thus reducing the possibility ofperiprosthetic bone resorption (see e.g., Fahlgren et al., “FluidPressure and Flow as a Cause of Bone Resorption,” Acta Orthopaedica 81:508-516, 2010 which is incorporated herein by reference). The fluiddeflector structures are fabricated from polyethylene and include a bandlinking an edge of each of a series of the fluid deflector structures ata set orientation relative to the circumference of the band. The base ofthe femoral component neck and the top of the femoral component stem aremachined to include small surface grooves positioned to stabilize thefluid deflection structures. Each groove corresponds to the size andshape of the band linking a series of the fluid deflector structures(see, e.g. FIG. 6).

Fluid deflector structures are created from polyethylene in suitableshapes and sizes to line the border between the titanium stem and thefemur and configured to deflect synovial fluid away from the stem-boneinterface in vivo. Compression molding is used to form the polymericfluid deflector structures directly onto the metallic stem at the siteof the groove. See e.g., U.S. Pat. No. 5,879,404, “Acetabular Cups andMethods of their Manufacture,” issued to Bateman et al. and U.S. Pat.No. 6,368,354, “Acetabular Bearing Assembly for Total Hip Joints,”issued to Burstein, which are each incorporated herein by reference.Fluid deflector structures approximately 1 cm long and 0.5 cm in widthare cast to protrude around the circumference of the femoral stem in aconfiguration predicted to divert synovial fluid away from the bone-steminterface and to reduce the transient synovial fluid pressure duringphysiological use of the joint. The fluid deflector structures areflexible, but firm enough to remain extended above the surface of theprosthesis and positioned to guide synovial fluid flow away from thestem-bone interface in vivo. See FIGS. 2 and 4. For example, a model hipjoint subjected to axial and torsional forces displays high and lowpressure in the proximal posterior and proximal anterior areasrespectively of the femoral stem (see e.g., Bartlett et al., “In VitroInfluence of Stem Surface Finish and Mantle Conformity on PressureGeneration in Cemented Hip Arthroplasty,” Acta Orthopaedica 80: 139-143,2009 which is incorporated herein by reference). Fluid pressuredifferentials drive high estimated synovial fluid flow rates (e.g., 20mm/s) and promote osteolysis that is observed in vivo in animal modelsof bone resorption (see e.g., Fahlgren et al., ibid., which isincorporated herein by reference). Fluid deflector structures areconstructed to occlude the interface between the prosthesis stem andfemoral bone and to reduce the transient pressure and divert the flow ofjoint fluid during physiological movement (see FIGS. 2 and 4).

The acetabular component of the artificial joint is constructed using aprocess of investment casting that employs titanium in the outer cup andtitanium and polyethylene in the inner cup (see e.g., U.S. Pat. No.5,665,118 ibid. which is incorporated herein by reference). During thecasing process, fluid deflector structures are constructed frompolyethylene and integrally formed at the margin of the outer cup. Thesefluid deflection structures are fabricated of a size and shape expectedto divert synovial fluid away from the interface between the pelvic boneand the outer cup during in vivo use. See, e.g. FIGS. 1-4. Manufactureof acetabular cups with titanium and polyethylene components isdescribed (see e.g., U.S. Pat. No. 5,879,404, ibid. which isincorporated herein by reference).

If desired, a hip joint prosthesis can be surgically implanted thatincludes both a femoral component with fluid deflection structuresattached and an acetabular cup with fluid deflection structuresattached, as described above. A medical caregiver can also select a hipjoint prosthesis that has fluid deflection structures attached to eitherthe femoral component or the acetabular component. In this situation,the corresponding components without fluid deflection structures can beobtained for implantation in conjunction with the component with fluiddeflection structures attached. For example, a femoral component with atitanium stem and a cobalt chromium alloy head is available from StrykerOrthopaedics, Mahwah, N.J. A acetabular component with a titanium shelland polyethylene bearings is available from Stryker Orthopaedics,Mahwah, N.J.

Example 2 An Artificial Knee Joint Including Fluid Deflector Structuresand an Encapsulation/Filtration Membrane Configured to RetainParticulates

A knee joint prosthesis is fabricated with fluid deflector structures onselect non-contact surfaces of the device. The fluid deflectorstructures are of a size, shape and position expected to divert jointfluids away from the interfaces of the device and the patient's bone,thereby reducing the likelihood of aseptic loosening of the prostheticimplant. The knee joint prosthesis is fabricated including a filtermembrane configured to capture debris particles arising in the jointthat can be present in the joint fluid. The fluid deflector structuresare configured to divert fluid flow through the filter, promotingremoval of debris particles from the joint fluid. Polyethylene and metaldebris particles in joint fluid, for example, are generally associatedwith osteolysis and loosening of artificial knee implants (see e.g.,Collier et al., “Osteolysis After Total Knee Arthroplasty: Influence ofTibial Baseplate Surface Finish and Sterilization of PolyethyleneInsert, Findings at Five to Ten Years Postoperatively,” J. Bone JointSurg. 87-A: 2702-2708, 2005 which is incorporated herein by reference).

The knee joint prosthesis comprises a femoral component and a tibialpart including a tibial spacer, and a tibial tray component. The tibialspacer is fabricated from polyethylene. See e.g., U.S. PatentApplication No. 2005/0055101 to Silheos, “Endoprosthesis of the Kneeand/or Other Joints,” which is incorporated herein by reference. Forexample, total knee replacement prostheses are commonly availableincluding polyethylene components. See, e.g., Xie, “A Systematic Reviewon Performance of the Vanguard® Complete Knee System,” Form No.BOI0500.0, REV083111, dated Jun. 30, 2011 and available from BiometInc., Warsaw, Ind., which is incorporated herein by reference. Othercomponents are metallic, preferably fabricated from titanium.

Fluid deflector structures are created from polyethylene and attached tothe knee prosthesis at non-contact surfaces of the prosthesiscomponents. The fluid deflector structures are of a size and shapeexpected to deflect synovial fluid away from the prosthesis-boneinterface. Compression molding methods are used to form the polymericfluid deflector structures directly onto the metallic femoral componentand tibial tray component (see e.g., U.S. Pat. No. 5,879,404, ibid. andU.S. Pat. No. 6,368,354, ibid, which are each incorporated by referenceherein). Fluid deflector structures approximately 1 cm long and 0.5 cmin width are molded to protrude over the boundary of the femoralcomponent and around the circumference of the tibial tray component. SeeFIGS. 8 and 9.

At the margin of the femoral component adjacent to the prosthesis-boneinterface a row of fluid deflector structures (see FIGS. 8 and 9)fabricated from polyethylene. The fluid deflector structures areconfigured to deflect synovial fluids away from the interface betweenthe femur and the implanted femoral component, and to reduce thevelocity of fluid flow in the joint, thus reducing periprosthetic boneresorption (see e.g., Fahlgren et al., ibid., which is incorporatedherein by reference). A row of polyethylene fluid deflector structuresis also attached to one or more of the tibial components and configuredto divert and impede fluid flows away from the interface between thetibial component and bone (see FIGS. 8 and 9).

The tibial tray component of the artificial joint is constructed using aprocess of investment casting (see e.g., U.S. Pat. No. 5,665,118 ibid.,which is incorporated by reference herein) that employs titanium alloys.Fluid deflector structures constructed from polyethylene are formed onthe margin of the tibial tray component to prevent synovial fluid fromentering the interface between the tibial tray baseplate and the tibia.See FIGS. 8-9 and Xie, ibid, which is incorporated by reference herein.Manufacture of prostheses with titanium and polyethylene components isas described (see e.g., U.S. Pat. No. 5,879,404, ibid, which isincorporated by reference herein).

The fluid deflector structures are flexible but firm enough to remainextended above the surface of the prosthesis and positioned to guidesynovial fluid flow from transient regions of high fluid pressure totransient regions of low fluid pressure. For example, a model jointsubjected to physiological axial and torsional forces displaysrelatively high and low pressure in the proximal posterior and proximalanterior areas respectively of a femoral stem (see e.g., Bartlett etal., 2009, ibid., which is incorporated by reference herein). Fluidpressure differentials result in high estimated fluid flow rates (e.g.,20 mm/s) which are associated with osteolysis and bone resorption (seee.g., Fahlgren et al., ibid., which is incorporated by referenceherein). Fluid deflector structures are configured and attached so as toocclude the interface of the femoral component and bone where theydivert and diffuse the flow of joint fluid (see FIG. 9). Fluid deflectorstructures are also of a size, shape and position to direct joint fluidflow toward a filter in the artificial joint. The combination of jointfluid flow diversion away from the bone-implant interface and toward afilter have synergetic effects to reduce the possible occurrence ofosteolysis and implant loosening.

To remove debris particles in the joint, a membrane filter is fabricatedto surround the artificial knee joint and trap particles present in thesynovial joint fluid. Particles can, for example, arise from wear on thepolyethylene or metal components of the joint. Particles can, forexample, arise from debris remaining after the implantation surgery.Particulate debris arising from the articulating surfaces or elsewherein the artificial joint are trapped by a membrane surrounding the jointcomponents. The membrane surrounding the joint components is configuredto trap debris particles while allowing joint fluid to pass through. Amembrane filter comprised of silicone, hydroxyl-ethyl-methacrylate andpolyvinylpirrolidone is fabricated to filter and trap particulates whichmay arise in the artificial joint (see U.S. Patent Application No.2005/0055101, ibid., which is incorporated by reference herein). Amembrane filter is constructed as a tube which attaches at one end tothe bone adjacent to the tibial tray-tibia bone interface, while thedistal end of the tube attaches to the femoral bone adjacent to thefemoral component interface. Membrane filters are composed of laminatesof polytetrafluoroethylene (PTFE) of different fibril lengths to trapparticles less than 0.2 microns in diameter while allowing fluids topass. See e.g.: U.S. Pat. No. 6,132,470, “Apparatus and Method forProtecting Prosthetic Joint Assembly from Wear,” to Berman; U.S. Pat.No. 5,879,406 “Artificial Joint Bioprosthesis for Mitigation of Wear,”to Lilley; U.S. Pat. No. 6,432,141 “Joint Prosthesis Assembly and Methodfor Installing Same,” to Stocks; US Patent Application No. 2003/0130740“Joint Prosthesis Assembly and Method for Installing Same,” to Stocks;U.S. Pat. No. 7,144,427 “Apparatus and Method for Advancing SynovialFluid in a Prosthetic Joint,” to Southworth; US Patent Application No.2004/0111162 “Apparatus and Method for Advancing Synovial Fluid in aProsthetic Joint,” to Southworth; US Patent Application No. 2005/0055101“Endoprosthesis of the Knee and/or other Joints,” to Sifneos; and U.S.Pat. No. 5,571,195 “Prosthesis for an Artificial Joint Having WearParticle Collection Capability,” to Johnson, which are each incorporatedherein by reference. Methods to attach a membrane filter to the boneadjacent to an artificial joint are described (see e.g.: U.S. PatentApplication No. 2005/0055101, ibid.; U.S. Pat. No. 4,731,088, “EnclosureMember for Prosthetic Joint” to Collier; and U.S. Pat. No. 6,132,470,ibid., which are each incorporated by reference herein). The membranefilter can, in some embodiments, include one or more stay rings tominimize the possibility of mechanical entrapment of the membranefilter. See U.S. Pat. No. 5,514,182 “Prosthetic Joint with SemipermeableCapsule with Reinforcing Ribs,” to Shea, which is incorporated herein byreference.

Example 3 An Artificial Hip Joint Including Actuated Fluid DeflectorStructures Configured to Divert Synovial Fluid and Associated DebrisParticles Away from Prosthesis-Bone Interface

An artificial hip joint prosthesis is fabricated with actuated fluiddeflector structures attached to select non-contact surfaces of thedevice. The fluid deflector structures are configured to divert jointfluid and associated debris particles away from interfaces between theartificial joint and the patient's bones and to reduce the transientfluid pressure at the interfaces during physiological use of the joint.The fluid deflector structures are attached to mechanisms that move thefluid deflection structures and thereby alter fluid flow in the joint.The altered fluid flow is configured to reduce the likelihood ofosteolysis and aseptic loosening of the prosthetic implant.

The hip joint prosthesis includes a femoral component which includes ahead (or ball), a neck and a stem which is implanted in the medullarycanal of the femur. There is also an acetabular component that includesan outer and inner cup with the outer cup attached to pelvic bone andthe inner cup forming a socket bearing the head of the femoralcomponent. The neck and stem of the femoral component are fabricatedfrom titanium (see e.g., U.S. Pat. No. 6,761,741, ibid., which isincorporated herein by reference). Actuated fluid deflector structuresare attached to non-contact surfaces on the edge regions of the femoralcomponent and the acetabular component. The fluid deflector structuresare configured to deflect synovial fluids and debris particles away fromthe interfaces between the prosthesis components and bone, and tomitigate the pressure of fluid flow on the prosthesis-bone interfaces,thus reducing the likelihood of periprosthetic bone resorption andartificial joint loosening (see e.g., Fahlgren et al., et al., ibid.,which is incorporated herein by reference).

The artificial joint is fabricated using processes of investment castingand milling. For example, a solid model comprised of a thermally labilematerial (e.g., wax) is made by injection molding and then a ceramicshell is created by coating the solid wax model. The ceramic shell isrecovered after melting the solid model and used as a mold to cast thecomponents of the prosthesis. See e.g., U.S. Pat. No. 5,665, ibid.,which is incorporated herein by reference. A groove is milled around thecircumference of the femoral component at the base of the neck tostabilize attached actuated fluid deflector structures. A groove is alsomilled around the circumference of the acetabular component in the outercup to stabilize attached actuated fluid deflector structures.

Actuated fluid deflector structures are constructed frompolydimethylsiloxane (PDMS, available from Dow Corning Corp., Midland,Mich.) containing permanently magnetic nanoparticles. Carbon coated ironparticles approximately 70 nm in diameter (available from M K ImpexCorp., Missisauga, ON, Canada) are dispersed in PDMS and spin cast toobtain fluid deflector structures approximately 1 cm long and 3 mm wide.See e.g., Willem van Engen, Master's Thesis: “Artificial cilia formicrofluidics exploring the use of a horizontally microstructuredferromagnetic PDMS composite,” Eindhoven University of Technology, 2008,Eindhoven, Netherlands, which is incorporated herein by reference. Thefluid deflector structures are magnetized by repeated movement of apermanent magnet with a magnetic field of about 500 mTesla along thelong axis of the fluid deflector structures. The fluid deflectorstructures are attached to a polymeric band by adhesion and the bands,containing approximately 2 fluid deflector structures per centimeter,are inserted in the grooves of the femoral and acetabular components.

Magnetic fluid deflector structures approximately 1 cm long and 3 mm inwidth are positioned around the circumference of the femoral stem andthe acetabular cup in positions predicted to divert synovial fluid awayfrom the bone-stem interface and to mitigate transient high pressure inthe joint fluid due to physiological movement of the joint. The fluiddeflector structures are flexible but firm enough to remain extendedabove the surface of the prosthesis and positioned to guide synovialfluid flow. For example, a model hip joint subjected to axial andtorsional forces displays high and low pressure in the proximalposterior and proximal anterior areas respectively of the femoral stem(see e.g., Bartlett et al., 2009, ibid., which is incorporated herein byreference). Fluid pressure differentials and high estimated fluid flowrates (e.g., 20 mm/s) promote osteolysis and bone resorption (see e.g.,Fahlgren et al., ibid., which is incorporated herein by reference).Magnetic fluid deflector structures are configured to mitigate fluidflow and pressure at the interface of the prosthesis and bone in vivo.The magnetic fluid deflector structures can be fabricated frompolyethylene including magnetic nanoparticles. See: Chatterjee et al.,“Synthesis of Polyethylene Magnetic Nanoparticles,” European Cells andMaterials 3(2): 98-101 (2002); Wang et al., “Novel Magnetic PolyethyleneNanocomposites Produced by Supported Nanometre Magentic Ziegler-NattaCatalyst,” Polymer International 49: 184-188 (2000); Millan et al.,“Magnetic Polymer Nanocomposites,” chapter 17 in Polymer Nanocomposites,Mai and Yu, eds. CRC Press, 2006; and Killeya, “First Plastic MagnetsCreated,” New Scientist (30 Aug. 2004), which are each incorporatedherein by reference.

A permanent magnet is constructed within the femoral component andconfigured to actuate the magnetic deflectors. A permanent magnet with amagnetic field of approximately 500 mTesla is placed in the stem regionof the femoral component to form a magnetic field configured to interactwith the magnetic fluid deflector structures on the femoral andacetabular components as the hip joint moves. The permanent magnetwithin the femoral component has a size, shape and position expected tocreate a magnetic field that is roughly perpendicular to the fluiddeflector structures. For example, a magnetic field of approximately 50mTesla applied perpendicular to the magnetic deflectors causes adeflection of approximately 0.5 millimeter in an artificial cilia (seevan Engen, ibid., which is incorporated herein by reference).

Alternatively, an electromagnet can be used to actuate the fluiddeflector structures. See US Patent Application No. 2008/0306324“Magnetic Joint Implant,” to Bonutti and Beyers, which is incorporatedherein by reference. Reversing the direction of electrical current inthe electromagnet switches the magnetic field direction by 180 degreesand reverses the direction of movement of the magnetic fluid deflectorstructures. An electromagnet can be used to create a magnetic field ofapproximately 500 mTesla, increasing the deflection of the magneticfluid deflector structures by 10 fold relative to a 50 mTesla magneticfield. Moreover, rapid switching of the direction of the magnetic fieldwill result in “beating” of the magnetic fluid deflector structures toactively divert synovial fluid flow away from prosthesis-boneinterfaces. The electromagnet can be empowered by a battery orpiezoelectric elements in the artificial hip prosthesis. Piezoelectricdevices suitable to capture and store energy from the movement of anartificial joint are known (see e.g., Keawboonchuay et al., “MaximumPower Generation in a Piezoelectric Pulse Generator,” IEEE TransactionsOn Plasma Science, 31: 123-128, 2003, which is incorporated herein byreference).

Example 4 An Artificial Hip Joint Including Actuated Fluid DeflectorStructures Configured to Capture Debris Particles

A hip joint prosthesis is fabricated with actuated fluid deflectorstructures on select non-contact surfaces of the device. The actuatedfluid deflector structures are configured to divert joint fluid anddebris particles away from the interface regions between the implantedartificial joint and the patient's bones. Also the actuated fluiddeflector structures include distal edge regions with adhesive tips. Theadhesive regions of the actuated fluid deflector structures areconfigured to capture and sequester debris particles in the joint fluid.Debris particles within the joint fluid are associated with an increasedlikelihood of osteolysis and aseptic loosening of the prostheticimplant.

The hip joint prosthesis includes a femoral component which includes ahead (or ball), a neck, and a stem which is configured to be implantedin the medullary canal of the femur. The hip joint prosthesis alsoincludes an acetabular component that includes an outer and inner cup,with the outer cup configured to be attached to pelvic bone and theinner cup forming a socket that bears the head of the femoral componentin vivo. The neck and stem of the femoral component are made fromtitanium (see e.g., U.S. Pat. No. 6,761,741, ibid., which isincorporated herein by reference).

Actuated fluid deflector structures are formed at the boundaries of thefemoral component and the acetabular component. The fluid deflectorstructures are configured to deflect synovial fluid flow and associateddebris particles away from the interfaces between the prosthesiscomponents and bone and to mitigate transient joint fluid pressure onthe prosthesis-bone interfaces during physiological use of the joint.The fluid deflector structures are also configured to capture debrisparticles in the joint fluid, thus reducing the likelihood ofperiprosthetic bone resorption and artificial joint loosening (see e.g.,Fahlgren et al., ibid., which is incorporated herein by reference).

The artificial joint is fabricated using processes of investmentcasting, milling and compression molding. For example, a solid modelcomprised of a thermally labile material (e.g., wax) is made byinjection molding and then a ceramic shell is created by coating thesolid wax model. The ceramic shell is recovered after melting the solidmodel and used as a mold to cast the components of the prosthesis. Seee.g., U.S. Pat. No. 5,665,118, ibid., which is incorporated herein byreference. A series of cavities are cast around the circumference of thefemoral component and at the base of the neck of the acetabularcomponent, with associated apertures within non-contact surfaces of theprosthesis. These cavities are configured to contain actuated fluiddeflector structures with size, shape, number and position as requiredby the specific prosthesis design.

Magnetic actuated fluid deflector structures are constructed frompolydimethylsiloxane (PDMS, available from Dow Corning Corp., Midland,Mich.) containing permanently magnetic nanoparticles. Carbon coated ironparticles approximately 70 nm in diameter (available from M K ImpexCorp., Missisauga, ON, Canada) are dispersed in PDMS to form acomposite. This composite is then cast in the cavities of the femoraland acetabular components to form fluid deflector structuresapproximately 1 cm long and 3 mm wide protruding from the cavities (seee.g., van Engen, ibid., which is incorporated herein by reference). Eachfluid deflector structure includes a proximal end that is positionedwithin the associated cavity, the proximal end of a size and shape to beblocked from leaving the cavity by the size and shape of the associatedaperture. Each fluid deflector structure includes a region traversingthe aperture. Each fluid deflector structure also includes a functionalregion approximately 1 cm long and 3 mm wide external to the cavity andaperture. The fluid deflector structures are magnetized by repeatedmovement of a permanent magnet along the long axis of the deflectorswith a magnetic field of about 500 mTesla. The fluid deflectorstructures also include distal edge regions which contain adhesive tipsconfigured to capture and retain debris particles. Artificial actuatedcilia which adhere to particles and are used for propelling particles(antifouling) and trapping particles (filtration) are described (seee.g., Bhattacharya et al., “Propulsion and Trapping of Microparticles byActive Cilia Arrays,” Langmuir 28: 3217-3226, (2012) which isincorporated herein by reference).

A permanent magnet is constructed in the neck of the femoral componentto actuate the magnetic fluid deflector structures with a magnetic fieldthat is oriented substantially perpendicular to the deflectors. Apermanent magnet with a magnetic field of approximately 500 mTesla isplaced in the neck region of the femoral component to actuate themagnetic fluid deflector structures on the femoral and acetabularcomponents as the hip joint moves. For example, a magnetic field ofapproximately 50 mTesla applied perpendicular to magnetic cilia has beenshown to cause a deflection of approximately 0.5 millimeter (see vanEngen, ibid., which is incorporated herein by reference). See also USPatent Application No. 2006/0149386, “Joint Prosthesis,” to Clarke andLee, which is incorporated by reference herein.

Magnetic fluid deflector structures with distal edge regions thatcontain adhesive tips are positioned around the circumference of thefemoral stem and the acetabular cup. The position, size, shape, numberand orientation of the fluid deflector structures on each prosthesiscomponent is configured to divert synovial joint fluid and associateddebris particles away from the bone-prosthesis interfaces. Each of thefluid deflector structures is also configured to trap debris particlesfrom synovial joint fluid with the adhesive tips attached to the distaledge regions of the fluid deflector structures. Models to calculate theoptimal adhesive force and stiffness for the fluid deflector structuresto trap particles are described (see Bhattacharya et al., ibid., whichis incorporated herein by reference). Actuated magnetic fluid deflectorstructures with distal edge regions that contain adhesive tips areconfigured to move in response to the motion of a magnet positionedwithin the femoral component. Physiological movement of the artificialhip joint moves the magnet within the femoral stem into proximity of thefluid deflector structures and causes the fluid deflector structures tobend or flex in response to the magnetic field. Movement of the fluiddeflector structures promotes directed fluid flow and trapping of debrisparticles (see e.g., van Engen, ibid. and Bhattacharya et al., ibid.,which are each incorporated herein by reference). Repeated “beating” ofthe fluid deflector structures during regular activities, e.g., walking,running, sitting, reclining, or sleeping, acts to divert the flow ofsynovial fluid away from the prosthesis-bone interfaces and traps debrisparticles within the fluid with the adhesive tips at the distal edgeregions of the fluid deflector structures. Thus, the artificial hipjoint with actuated adhesive fluid deflector structures reduces thelikelihood of osteolysis, periprosthetic bone resorption and prosthesisloosening in vivo.

Example 5 An Artificial Hip Joint Including Fluid Deflector StructuresConfigured to Respond to a Magnetic Field

A hip joint prosthesis is fabricated with actuated fluid deflectorstructures on select non-contact surfaces of the device. The actuatedfluid deflector structures are configured to divert joint fluid anddebris particles away from the interface regions between the implantedartificial joint and the patient's bones. Debris particles within thejoint fluid are associated with an increased likelihood of osteolysisand aseptic loosening of the prosthetic implant.

The hip joint prosthesis includes a femoral component which includes ahead (or ball), a neck, and a stem which is configured to be implantedin the medullary canal of the femur. The hip joint prosthesis alsoincludes an acetabular component that includes an outer and inner cup,with the outer cup configured to be attached to pelvic bone and theinner cup forming a socket that bears the head of the femoral componentin vivo. The neck and stem of the femoral component are predominatelyfabricated from titanium (see e.g., U.S. Pat. No. 6,761,741, ibid.,which is incorporated herein by reference).

The artificial joint is fabricated using processes of investmentcasting, milling and compression molding. For example, a solid modelcomprised of a thermally labile material (e.g., wax) is made byinjection molding and then a ceramic shell is created by coating thesolid wax model. The ceramic shell is recovered after melting the solidmodel and used as a mold to cast the components of the prosthesis. Seee.g., U.S. Pat. No. 5,665,118, ibid., which is incorporated herein byreference. A series of cavities are cast around the circumference of theacetabular cup, with associated apertures within non-contact surfaces ofthe prosthesis. The cavities in the acetabular cup are configured withsubstantially circular sides, to contain substantially circularmechanisms attached to fluid deflector structures, of size, shape,number and position as required by the specific prosthesis design.

A permanent magnet is constructed in the neck of the femoral component,with a magnetic field that is oriented substantially along the long axisof the neck of the femoral component. FIG. 11 illustrates the permanentmagnet 1100 embedded within the femoral stem component 187, with theaxis of polarity of the magnet (represented as + and − in the Figure)oriented substantially along the long axis of the femoral stem component187. A permanent magnet with a magnetic field of approximately 500mTesla is placed in the neck region of the femoral component to actuatethe magnetic fluid deflector structures on the acetabular cup thatapproach the permanent magnet 1100 as the hip joint moves. For example,a magnetic field of approximately 50 mTesla applied perpendicular tomagnetic cilia has been shown to cause a deflection of approximately 0.5millimeter (see van Engen, ibid., which is incorporated herein byreference). See also US Patent Application No. 2006/0149386, “JointProsthesis,” to Clarke and Lee, which is incorporated by referenceherein.

As illustrated in FIG. 11, each of the fluid deflecting structures 140A,140B is attached to a mechanism 1110A, 1110B that includes a ball-likeend configured to fit within the cavities in the acetabular cup, and anattached rod projecting away from the non-contact surface of theprosthesis along the long axis of the fluid deflecting structures 140A,140B. The ball-like end of the mechanism 1110A, 1110B is of a size andshape configured to fit within a corresponding cavity in the femoralstem component 187, and to rotate within the cavity. Each of the rodstructures of the mechanism 1110A, 1110B is a permanent magnet, with anaxis of polarity along the long axis of the rod. The polarity of thedistal end of the rod structure of a mechanism 1110A, 1110B is the sameas the polarity of the closer end of the permanent magnet 1100 embeddedwithin the femoral stem component 187. For example, FIG. 11 illustratesa permanent magnet 1100 embedded within the femoral stem component 187with a “north” polar end (“+”) at the end of the permanent magnet 1100adjacent to the femoral ball 182. Correspondingly, FIG. 11 shows thedistal ends of the rod structures of the mechanisms 1110A, 1110B asincluding a “north” polar end (“+”). Although the instant illustrationshows these ends as including a “north” polar end (“+”), embodimentsalso include those with corresponding “south” polar ends (“−”) on theend of the permanent magnet 1100 adjacent to the femoral ball 182 andthe distal ends of the rod structures of the mechanisms 1110A, 1110B.

Actuated fluid deflector structures 140A, 140B are formed at the edgeregion of the acetabular liner. The fluid deflector structures areconfigured to deflect synovial fluid flow and associated debrisparticles away from the interfaces between the prosthesis components andbone and to mitigate transient joint fluid pressure on theprosthesis-bone interfaces during physiological use of the joint.Magnetic actuated fluid deflector structures are constructed frompolydimethylsiloxane (PDMS, available from Dow Corning Corp., Midland,Mich.) around the core rods of the mechanism 1110A, 1110B. The PDMS iscast around the rod structures of the mechanisms 1110A, 1110B to formfluid deflector structures approximately 10 mm long and 3 mm wideprotruding from the cavities (see e.g., van Engen, ibid., which isincorporated herein by reference). Each fluid deflector structure 140A,140B includes a mechanism 1110A, 1110B including a rod structure with aproximal end that is positioned within the associated cavity, theproximal end of a size and shape to be blocked from leaving the cavityby the size and shape of the associated aperture while allowing forrotation within the cavity. Each fluid deflector structure 140A, 140Bincludes a region traversing the aperture. Each fluid deflectorstructure 140A, 140B also includes a functional deflector regionapproximately 10 mm long and 3 mm wide external to the cavity andaperture.

Magnetic fluid deflector structures 140A, 140B are positioned around thecircumference of the acetabular cup 175. The position, size, shape,number and orientation of the fluid deflector structures 140A, 140B isconfigured to divert synovial joint fluid and associated debrisparticles away from the bone-prosthesis interfaces. Actuated magneticfluid deflector structures 140A, 140B are configured to move in responseto the motion of the magnet 1100 positioned within the femoral stemcomponent 187. Physiological movement of the artificial hip joint movesthe magnet 1100 within the femoral stem 187 into proximity of the fluiddeflector structures 140A on the adjacent edge of the acetabular cup175. The proximity of the same-polarity magnetic fields causes the fluiddeflector structures 140A to bend or flex in response to the magneticfield in a direction away from the femoral stem 187. Movement of thefluid deflector structures 140 A promotes directed fluid flow away fromthe bone-prosthesis interface. Repeated “beating” of the fluid deflectorstructures 140A, 140 B in response to the relative re-positioning of thefluid deflector structures 140A, 140 B and the magnet 1100 positionedwithin the femoral stem component 187 during regular activities, e.g.,walking, running, sitting, reclining, or sleeping, acts to divert theflow of synovial fluid away from the prosthesis-bone interfaces. Thus,the artificial hip joint with embedded magnet 1100 and actuated fluiddeflector structures 140 A, 140 B reduces the likelihood of osteolysis,periprosthetic bone resorption and prosthesis loosening in vivo.

All of the above U.S. patents, U.S. patent application publications,U.S. patent applications, foreign patents, foreign patent applicationsand non-patent publications referred to in this specification and/orlisted in any Application Data Sheet, are incorporated herein byreference, to the extent not inconsistent herewith.

While various aspects and embodiments have been disclosed herein, otheraspects and embodiments will be apparent to those skilled in the art.The various aspects and embodiments disclosed herein are for purposes ofillustration and are not intended to be limiting, with the true scopeand spirit being indicated by the following claims.

What is claimed is:
 1. A artificial joint prosthesis, comprising: abone-facing surface of a artificial joint prosthesis, the bone-facingsurface configured to face a bone-prosthesis interface in vivo; anon-load bearing surface of the artificial joint prosthesis, thenon-load bearing surface adjacent to the bone-facing surface of theartificial joint prosthesis; at least one fluid deflection structurepositioned adjacent to the non-load bearing surface; and a mechanismattached to the fluid deflection structure, the mechanism operable tomove the fluid deflection structure to direct synovial fluid away fromthe bone-prosthesis interface in vivo.
 2. A artificial joint prosthesis,comprising: a bone-facing surface of a artificial joint prosthesis, thebone-facing surface configured to face a bone-prosthesis interface invivo; a non-contact surface of the artificial joint prosthesis, thenon-contact surface adjacent to the bone-facing surface of theartificial joint prosthesis; at least one fluid deflection structurepositioned adjacent to the non-contact surface, the fluid deflectionstructure positioned to deflect synovial fluid away from thebone-prosthesis interface in vivo; and a mechanism attached to the fluiddeflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo. 3.-23. (canceled)
 24. The artificialjoint prosthesis of claim 2, wherein the mechanism attached to the fluiddeflection structure is substantially enclosed within the artificialjoint prosthesis.
 25. The artificial joint prosthesis of claim 2,wherein the mechanism attached to the fluid deflection structurecomprises: an actuator attached to the fluid deflection structure andconfigured to move the fluid deflection structure; and a batteryconfigured to provide energy to the actuator.
 26. The artificial jointprosthesis of claim 2, wherein the mechanism attached to the fluiddeflection structure includes piezoelectric material, the piezoelectricmaterial configured to drive movement of the at least one fluiddeflection structure.
 27. The artificial joint prosthesis of claim 2,wherein the mechanism attached to the fluid deflection structureincludes at least one magnetic actuator, the magnetic actuatorconfigured to drive movement of the at least one fluid deflectionstructure.
 28. The artificial joint prosthesis of claim 2, comprising:an aperture in the non-contact surface of the artificial jointprosthesis; a substantially round cavity in the artificial jointprosthesis adjacent to the aperture; the mechanism including asubstantially round element of a size and shape to correspond to thesubstantially round cavity, the substantially round element positionedwithin the substantially round cavity and configured to move within thesubstantially round cavity; and the at least one fluid deflectionstructure attached to the substantially round element and projectingthrough the aperture.
 29. The artificial joint prosthesis of claim 2,comprising: at least one first magnet integral to the artificial jointprosthesis; and at least one second magnet attached to the fluiddeflection structure, wherein the mechanism attached to the fluiddeflection structure is configured to move in accord with a magneticfield established by the at least one first magnet.
 30. The artificialjoint prosthesis of claim 2, comprising: at least one first magnetintegral to the artificial joint prosthesis; and at least one secondmagnet attached to the fluid deflection structure, wherein the mechanismattached to the fluid deflection structure is configured to allow the atleast one second magnet to move the fluid deflection structure in accordwith a magnetic field established by the at least one first magnet. 31.The artificial joint prosthesis of claim 2, comprising: at least twocomponents, each of which include at least one fluid deflectionstructure positioned adjacent to a non-contact surface, and each ofwhich include the mechanism attached to the fluid deflection structure,each of the mechanisms operable to move each of the fluid deflectionstructure to direct synovial fluid away from the bone-prosthesisinterface in vivo.
 32. A hip joint prosthesis, comprising: a bone-facingsurface of a hip joint prosthesis, the bone-facing surface configured toface a bone-prosthesis interface in vivo; a non-contact surface of thehip joint prosthesis, the non-contact surface adjacent to thebone-facing surface of the hip joint prosthesis; at least one fluiddeflection structure positioned adjacent to the non-contact surface, thefluid deflection structure positioned to deflect synovial fluid awayfrom the bone-prosthesis interface in vivo; and a mechanism attached tothe fluid deflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo. 33.-57. (canceled)
 58. The hip jointprosthesis of claim 32, wherein the mechanism attached to the fluiddeflection structure is substantially enclosed within the artificialjoint prosthesis.
 59. The hip joint prosthesis of claim 32, wherein themechanism attached to the fluid deflection structure comprises: anactuator attached to the fluid deflection structure and configured tomove the fluid deflection structure; and a battery configured to provideenergy to the actuator.
 60. The hip joint prosthesis of claim 32,wherein the mechanism attached to the fluid deflection structureincludes piezoelectric material, the piezoelectric material configuredto drive movement of the fluid deflection structure.
 61. The hip jointprosthesis of claim 32, wherein the mechanism attached to the fluiddeflection structure includes at least one magnetic actuator, themagnetic actuator configured to drive movement of the fluid deflectionstructure.
 62. The hip joint prosthesis of claim 32, comprising: anaperture in the non-contact surface of the hip joint prosthesis; asubstantially round cavity in the hip joint prosthesis adjacent to theaperture; the mechanism including a substantially round element of asize and shape to correspond to the substantially round cavity, thesubstantially round element positioned within the substantially roundcavity and configured to move within the substantially round cavity; andthe at least one fluid deflection structure attached to thesubstantially round element and projecting through the aperture.
 63. Thehip joint prosthesis of claim 32, comprising: at least one first magnetintegral to the hip joint prosthesis; and at least one second magnetattached to the fluid deflection structure, wherein the mechanismattached to the fluid deflection structure is configured to move inaccord with a magnetic field established by the at least one firstmagnet.
 64. The hip joint prosthesis of claim 32, comprising: at leastone first magnet integral to the hip joint prosthesis; and at least onesecond magnet attached to the fluid deflection structure, wherein themechanism attached to the fluid deflection structure is configured toallow the at least one second magnet to move the fluid deflectionstructure in accord with a magnetic field established by the at leastone first magnet.
 65. The hip joint prosthesis of claim 32, comprising:at least one acetabular component, wherein the acetabular componentincludes at least one fluid deflection structure positioned adjacent tothe non-contact surface and at least one mechanism attached to the atleast one fluid deflection structure; and at least one femoralcomponent, wherein the femoral component includes at least one fluiddeflection structure positioned adjacent to the non-contact surface andat least one mechanism attached to the at least one fluid deflectionstructure.
 66. A knee joint prosthesis, comprising: a bone-facingsurface of a knee joint prosthesis, the bone-facing surface configuredto face a bone-prosthesis interface in vivo; a non-contact surface ofthe knee joint prosthesis, the non-contact surface adjacent to thebone-facing surface of the knee joint prosthesis; at least one fluiddeflection structure positioned adjacent to the non-contact surface, thefluid deflection structure positioned to deflect synovial fluid awayfrom the bone-prosthesis interface in vivo; and a mechanism attached tothe fluid deflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo. 67.-91. (canceled)
 92. The knee jointprosthesis of claim 66, wherein the mechanism attached to the fluiddeflection structure is substantially enclosed within the artificialjoint prosthesis.
 93. The knee joint prosthesis of claim 66, wherein themechanism attached to the fluid deflection structure comprises: anactuator attached to the fluid deflection structure and configured tomove the fluid deflection structure; and a battery configured to provideenergy to the actuator.
 94. The knee joint prosthesis of claim 66,wherein the mechanism attached to the fluid deflection structureincludes piezoelectric material, the piezoelectric material configuredto drive movement of the fluid deflection structure.
 95. The knee jointprosthesis of claim 66, wherein the mechanism attached to the fluiddeflection structure includes at least one magnetic actuator, themagnetic actuator configured to drive movement of the fluid deflectionstructure.
 96. The knee joint prosthesis of claim 66, comprising: anaperture in the non-contact surface of the knee joint prosthesis; asubstantially round cavity in the knee joint prosthesis adjacent to theaperture; the mechanism including a substantially round element of asize and shape to correspond to the substantially round cavity, thesubstantially round element positioned within the substantially roundcavity and configured to move within the substantially round cavity; andthe at least one fluid deflection structure attached to thesubstantially round element and projecting through the aperture.
 97. Theknee joint prosthesis of claim 66, comprising: at least one first magnetintegral to the knee joint prosthesis; and at least one second magnetattached to the fluid deflection structure, wherein the mechanismattached to the fluid deflection structure is configured to move inaccord with a magnetic field established by the at least one firstmagnet.
 98. The knee joint prosthesis of claim 66, comprising: at leastone first magnet integral to the knee joint prosthesis; and at least onesecond magnet attached to the fluid deflection structure, wherein themechanism attached to the fluid deflection structure is configured toallow the at least one second magnet to move the fluid deflectionstructure in accord with a magnetic field established by the at leastone first magnet.
 99. The knee joint prosthesis of claim 66, comprising:at least one femoral component, wherein the femoral component includesat least one fluid deflection structure positioned adjacent to thenon-contact surface and at least one mechanism attached to the at leastone fluid deflection structure; and at least one tibial component,wherein the tibial component includes at least one fluid deflectionstructure positioned adjacent to the non-contact surface and at leastone mechanism attached to the at least one fluid deflection structure.100. A shoulder joint prosthesis, comprising: a bone-facing surface of ashoulder joint prosthesis, the bone-facing surface configured to face abone-prosthesis interface in vivo; a non-contact surface of the shoulderjoint prosthesis, the non-contact surface adjacent to the bone-facingsurface of the shoulder joint prosthesis; at least one fluid deflectionstructure positioned adjacent to the non-contact surface, the fluiddeflection structure positioned to deflect synovial fluid away from thebone-prosthesis interface in vivo; and a mechanism attached to the fluiddeflection structure, the mechanism operable to move the fluiddeflection structure to direct synovial fluid away from thebone-prosthesis interface in vivo. 101.-125. (canceled)
 126. Theshoulder joint prosthesis of claim 100, wherein the mechanism attachedto the fluid deflection structure is substantially enclosed within theshoulder joint prosthesis.
 127. The shoulder joint prosthesis of claim100, wherein the mechanism attached to the fluid deflection structurecomprises: an actuator attached to the fluid deflection structure andconfigured to move the fluid deflection structure; and a batteryconfigured to provide energy to the actuator.
 128. The shoulder jointprosthesis of claim 100, wherein the mechanism attached to the fluiddeflection structure includes piezoelectric material, the piezoelectricmaterial configured to drive movement of the at least one fluiddeflection structure.
 129. The shoulder joint prosthesis of claim 100,wherein the mechanism attached to the fluid deflection structureincludes at least one magnetic actuator, the magnetic actuatorconfigured to drive movement of the at least one fluid deflectionstructure.
 130. The shoulder joint prosthesis of claim 100, wherein themechanism attached to the fluid deflection structure includespiezoelectric material, the piezoelectric material configured to drivemovement of the fluid deflection structure.
 131. The shoulder jointprosthesis of claim 100, wherein the mechanism attached to the fluiddeflection structure includes at least one magnetic actuator, themagnetic actuator configured to drive movement of the fluid deflectionstructure.
 132. The shoulder joint prosthesis of claim 100, comprising:an aperture in the non-contact surface of the artificial shoulder jointprosthesis; a substantially round cavity in the artificial shoulderjoint prosthesis adjacent to the aperture; the mechanism including asubstantially round element of a size and shape to correspond to thesubstantially round cavity, the substantially round element positionedwithin the substantially round cavity and configured to move within thesubstantially round cavity; and the at least one fluid deflectionstructure attached to the substantially round element and projectingthrough the aperture.
 133. The shoulder joint prosthesis of claim 100,comprising: at least one first magnet integral to the artificialshoulder joint prosthesis; and at least one second magnet attached tothe fluid deflection structure, wherein the mechanism attached to thefluid deflection structure is configured to move in accord with amagnetic field established by the at least one first magnet.
 134. Theshoulder joint prosthesis of claim 100, comprising: at least one firstmagnet integral to the artificial shoulder joint prosthesis; and atleast one second magnet attached to the fluid deflection structure,wherein the mechanism attached to the fluid deflection structure isconfigured to allow the at least one second magnet to move the fluiddeflection structure in accord with a magnetic field established by theat least one first magnet.
 135. The shoulder joint prosthesis of claim100, comprising: at least one glenoid component, wherein the glenoidcomponent includes at least one fluid deflection structure positionedadjacent to the non-contact surface and at least one mechanism attachedto the at least one fluid deflection structure; and at least one humeralcomponent, wherein the humeral component includes at least one fluiddeflection structure positioned adjacent to the non-contact surface andat least one mechanism attached to the at least one fluid deflectionstructure.